Grade 8 · Math

8th grade Find a missing side of a right triangle worksheet

6 printable versionsChallenge Me10 questions · answer keyFree · no account

Level: Building Confidence · On Level · Challenge Me

When it’s done, scan the sheet with your phone and PencilGo marks it and picks the next one. Create a free account

Version

Find a missing side of a right triangle

Grade 8 Math Worksheet - Challenge Me

NameDate

Circle the best answer, or write your answer on the line.

Esme draws a right triangle and wants the exact length of the missing leg. Written as a square root, how long is it, in cm?
Luz sketches a very thin right triangle in pencil. Written as a square root, how long is the missing leg, in inches?
Milo cuts a right triangle from paper for a model sail. To the nearest tenth of a centimeter, how long is the hypotenuse?
Noah plans a right-triangle quilt patch. The cat has already claimed the fabric. To the nearest tenth of an inch, how long is the hypotenuse?
Pia's class marks a right-triangle flower bed with string. To the nearest tenth of a foot, how long is the hypotenuse?
Ren draws a long, thin right triangle in pencil. To the nearest tenth of a centimeter, how long is the hypotenuse?
Zee lays a right triangle of tiles. One leg has no label yet. To the nearest tenth of an inch, how long is the missing leg?
Ari's garden club plans a right-triangle bed. A snail is already waiting. To the nearest tenth of a foot, how long is the missing leg?
Esme glues ribbon all the way around a paper right triangle. How many inches of ribbon go around it?
Luz's class puts a small fence around a right-triangle flower bed. How many feet of fence go all the way around?

8th grade Find a missing side of a right triangle worksheet – printable — Print: 1 2 3 4 5 6

About this worksheet

Find a missing side of a right triangle. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

I can find the hypotenuse from the two legs: square, add, then find the side.
I can find a missing leg: take the leg's square off the big square, then find the side.
I can write a side that is not a whole number as a square root, like √52, or round it to the nearest tenth.

Standard: 8.G.B.7

Words to know

leg: One of the two sides that meet at the right-angle mark.

hypotenuse: The side across from the right angle. It is the longest side.

square root (√): The number that times itself makes the area: √49 = 7.

exact: Not rounded: √52 is exact; 7.2 is rounded.

nearest tenth: Rounded to one decimal place, like 7.2.

perimeter: The distance all the way around a shape.

Common mistakes

Your child added the lengths of the two short sides to get the long side. The squares on the short sides add up to the square on the long side; the lengths do not. Try it on a 3, 4, 5 triangle: 3 + 4 is 7, but the long side is 5.

Your child found the area of the missing square but gave that area as the side's length. The side is the number that times itself makes the area.

Your child subtracted one side's length from the other to get a missing short side. The square on the long side minus the square on the known short side gives the missing square. Try it on a 3, 4, 5 triangle: 5 − 4 is 1, but the missing side is 3.

What to say

Ask: which number times itself makes 25?

Questions parents ask

What is the most common mistake with find a missing side of a right triangle?

Are these 8th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More grade 8 math

See all grade 8 math

Every sheet you scan goes into your child’s record: dated, marked and ready for the year-end portfolio. Homeschool records