Grade 8 · Math

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

6 printable versionsBuilding Confidence10 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 - Building Confidence

NameDate

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

Ari cuts a right triangle from card paper for an art project. How long is the hypotenuse, in inches?
Bo's drawing robot draws a right triangle and then beeps very proudly. How long is the hypotenuse, in cm?
Esme's class marks out a right-triangle flower bed with string. How long is the hypotenuse, in feet?
Jun sews a right-triangle quilt patch. How long is the hypotenuse of the patch, in inches?
Kira draws a right triangle on poster paper but forgets to label one leg. How long is that leg, in feet?
Luz cuts a right triangle out of felt. The scissors are extra sharp today. How long is the unlabeled leg, in inches?
Noah draws a long, thin right triangle with a crayon. How long is the unlabeled leg, in cm?
Pia lays a right triangle of foam tiles on the gym floor. How long is the unlabeled leg, in inches?
9.
Ren must find the hypotenuse of a right triangle drawn on paper. Which first step is right?
- Subtract the squares: 36² − 15²
- Add the sides: 15 + 36
- Add the squares: 15² + 36²
10.
Ari's robot shows a right triangle and blinks at the missing leg. Which first step finds that leg?
- Subtract the sides: 26 − 10
- Subtract the squares: 26² − 10²
- Add the squares: 10² + 26²

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