Diagonal In A Sentence | Clear Examples Today

You’ve seen the word diagonal in math class, on a floor plan for a room, and in little life moments like a strap worn across a chest. In writing, diagonal in a sentence can trip you up.

This page fixes that pause. You’ll get copy-ready examples for school or work.

What “Diagonal” Means In Plain English

A diagonal is a straight line that runs from one corner of a shape to the opposite corner. In regular writing, “diagonal” also describes anything that slants across instead of running straight up-and-down or side-to-side.

Two checks keep you on track:

• If you can put “a” or “the” before it, you’re often using it as a noun: a diagonal, the diagonal.
• If it describes a thing, you’re using it as an adjective: a diagonal line, diagonal stripes.

Diagonal Use Cases And Sentence Templates

Writers use “diagonal” in a handful of repeatable ways. The table below shows the main uses, the grammar role, and a model sentence you can mirror.

How “Diagonal” Works	Grammar Role	Model Sentence
Corner-to-corner line in a shape	Noun	The diagonal of the square measures 10 cm.
Slanted line on paper or a screen	Adjective	Draw a diagonal line from the top left to the bottom right.
Direction of movement	Adjective	She stepped in a diagonal path to avoid the puddle.
Pattern or design detail	Adjective	The shirt has diagonal stripes that make it look longer.
Cut or seam across a surface	Adjective	Use a diagonal cut so the tape edge won’t peel as fast.
Across-the-body strap or sling	Adjective	The bag’s diagonal strap kept it from sliding off.
Shortcut line in a grid or map	Noun	The diagonal across the park saved us five minutes.
In a coordinate plane	Noun or adjective	The graph has a diagonal that rises one unit for each unit to the right.

Using Diagonal In Sentences With Direction Words

When “diagonal” points to direction, pair it with a clear anchor: left/right, corner names, or a reference object. That keeps the sentence from feeling vague.

Anchor The Direction With Two Points

Two points make the slant easy to picture and easy to draw.

• Place the ruler from the bottom left corner to the top right corner and draw a diagonal line.
• The crack runs on a diagonal from the window latch to the sill.
• He folded the paper on the diagonal, corner to corner.

Use A Noun After “Diagonal” For Clarity

“Diagonal” often reads best when it modifies a concrete noun like line, path, slash, seam, or crease.

• The editor marked a diagonal slash through the extra paragraph.
• We followed a diagonal path across the field to reach the gate.
• Add a diagonal crease so the paper pops open cleanly.

Diagonal In A Sentence For Math And Geometry Class

In math writing, “diagonal” usually shows up as a noun that names a segment, or as an adjective that labels a line you draw. Keep the structure tight and your units clear.

Use “The Diagonal Of” When You’re Naming A Measurement

This pattern reads clean in homework, lab reports, and exam responses.

• The diagonal of the rectangle is 13 cm, based on the Pythagorean theorem.
• Find the diagonal of the cube using the space diagonal formula.
• Because the diagonal of a square is longer than its side, the box won’t fit.

Use “Diagonal Line” When You’re Giving A Drawing Step

If the task is about construction, name the points and the tool you’re using.

• Connect the opposite vertices with a diagonal line, then label the intersection.
• Draw one diagonal line across the quadrilateral and count the two triangles you made.
• Sketch a diagonal line through the grid squares to show the shortest route.

If you want a dictionary-grade definition to cite in class notes, see Merriam-Webster’s definition of “diagonal”.

Diagonal Vs. Diagonally In Real Writing

“Diagonal” names the thing or describes the thing. “Diagonally” tells how something happens. A quick swap test keeps you from mixing them up:

• If you can replace the word with “slanted,” you likely want diagonal.
• If you can replace it with “at a slant,” you likely want diagonally.

Read it aloud and ask if the word names a thing or describes motion in your line.

Diagonal As A Noun

Use the noun when you mean the line itself.

• The diagonal splits the square into two matching triangles.
• Measure the diagonal before you buy the screen protector.

Diagonal As An Adjective

Use the adjective when it modifies another word.

• She drew diagonal arrows to show the flow.
• A diagonal seam can reduce bulky corners.

Diagonally As An Adverb

Use the adverb when it modifies a verb, adjective, or another adverb.

• The kite drifted diagonally across the sky.
• Stack the tiles diagonally to change the look of the room.

Where Diagonal Shows Up In Everyday Descriptions

You don’t need a worksheet to use “diagonal.” It fits any time you describe shape, spacing, or motion.

Clothes, bags, and straps

When you mean “across the body,” pair “diagonal” with the object so nobody has to infer what’s slanted.

• The diagonal strap rubbed her shoulder after the long walk.
• He adjusted the diagonal sling so the camera sat higher on his chest.

Photos, posters, and layouts

Design notes often call out a diagonal line or diagonal spacing. Add the reason so the reader knows what the slant is doing.

• Place the headline on a diagonal line to echo the mountain ridge in the photo.
• The diagonal spacing between icons keeps the grid from feeling boxed in.

Sports and quick movement

In action writing, “diagonally” is your friend, since it keeps the verb clean.

• She cut diagonally across the court and lost her defender.
• The midfielder drifted diagonally toward the far post.

Common Mistakes When Writing “Diagonal”

Most errors come from vague direction, missing nouns, or mixing the adjective with the adverb. Here are fixes you can apply.

Problem: “Diagonal” Without A Clear Reference

Weak: “Draw a diagonal.”

Stronger: “Draw a diagonal from the top left corner to the bottom right corner.”

Problem: Using “Diagonal” When You Mean “Diagonally”

Weak: “The runner moved diagonal.”

Stronger: “The runner moved diagonally.”

Problem: Forgetting The Noun In Non-Math Writing

Weak: “The logo has diagonal.”

Stronger: “The logo has diagonal lines that cut across the circle.”

Easy Ways To Make Diagonal Sentences Sound Natural

“Diagonal” is a crisp word, yet it can feel stiff if you pile too much math language around it. These small tweaks keep the sentence smooth.

Pick A Concrete Noun

Try line, path, stripe, cut, crease, seam, step, or arrow. One strong noun beats a longer phrase.

Keep The Verb Active

Strong verbs make the slant feel like motion, not jargon.

• “Cut,” “fold,” “trace,” “connect,” “cross,” “angle,” “tilt,” “slide,” “drift.”

Use A Quick Check For Reader Confusion

If a reader could ask “Diagonal where?”, add two points or a reference object and you’re done.

For a second reference that’s easy to cite, see Cambridge Dictionary’s entry for “diagonal”.

Sentence Examples You Can Copy And Adapt

Use these as starting points, then swap in your own subject, measurement, or object. Keep the structure; change the details.

School And Homework Examples

• The diagonal of the rectangle is longer than either side.
• After drawing the diagonal line, label the endpoints A and C.
• The diagram shows a diagonal that splits the shape into two equal parts.
• Write the proof using the diagonal as your shared side.

Everyday Writing Examples

• I hung the picture on a diagonal to match the stair angle.
• Sunlight spilled in a diagonal streak across the kitchen floor.
• The zipper runs on a diagonal, so the jacket opens wide at the neck.
• We cut the sandwich diagonally and shared it on the walk home.

Work And Technical Notes Examples

• Add a diagonal brace to stop the frame from wobbling.
• The crack formed on a diagonal across the tile after the drop.
• Route the cable diagonally behind the panel to keep it clear of the fan.
• Print the chart with diagonal labels so long names fit.

Patterns That Make “Diagonal” Easy To Place

If you’re stuck, use a pattern. Pick one, drop your details into the blanks, and you’ll get a clean sentence.

Pattern	When It Fits	Fill-In Example
The diagonal of the [shape] is [number] [unit].	Measurements in math or specs	The diagonal of the monitor is 27 inches.
Draw a diagonal line from [point A] to [point B].	Directions in tasks and worksheets	Draw a diagonal line from corner A to corner C.
[Thing] has diagonal [noun] that [verb] across [surface].	Design descriptions	The wallpaper has diagonal stripes that run across the hallway.
[Person/thing] moved diagonally toward [place].	Motion and action writing	The defender moved diagonally toward the sideline.
Make a diagonal [cut/crease/seam] to [reason].	Instructions and how-to notes	Make a diagonal cut to keep the edge from fraying.
A diagonal path across [area] saved [time/distance].	Maps and routes	A diagonal path across the lot saved ten steps.
The line rises on a diagonal as [x] increases.	Graphs and trends	The line rises on a diagonal as the temperature increases.

Mini Drills To Practice Without Overthinking

Practice works best when it’s small. Try these drills and you’ll stop second-guessing the word.

Drill 1: Pick The Role

Choose noun or adjective, then write one sentence.

1. Noun: write about the diagonal of a shape you can picture.
2. Adjective: write about diagonal lines in a pattern you’ve seen.

Drill 2: Swap In “Diagonally”

Write two sentences that describe motion, then rewrite them using “diagonally” so the verb is clear.

Drill 3: Add Two Points

Take a vague sentence like “Draw a diagonal line” and add corner names, grid squares, or left/right cues.

Quick Checklist Before You Submit Or Send

• Did you mean the line itself (noun) or a slanted feature (adjective)?
• If the sentence shows motion, did you switch to “diagonally”?
• Did you name two points or a clear reference so the direction is obvious?
• Did you attach units when you gave a measurement?
• Did you keep the sentence short enough to read once without re-reading?

If you’re using this page as a model, drop the phrase “diagonal in a sentence” into your own draft, then swap in your topic details. That’s it.

One last nudge: if you’re teaching this word, put the noun, adjective, and adverb forms on the board, then build three short examples together.