Grade 8 · Math

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

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Find a missing side of a right triangle

Grade 8 Math Worksheet

NameDate

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

Bo folds a paper right triangle for a mobile. How long is its hypotenuse, in cm?
Esme lays a right triangle of tiles on the floor of the art room. How long is the hypotenuse, in inches?
Kira's park map shows a right-triangle lawn. A duck is drawn in one corner. How long is the hypotenuse, in feet?
Milo cuts a big right-triangle patch for a class quilt. How long is the unlabeled leg, in inches?
Noah cuts a long right triangle from a paper strip. How long is the short leg, in cm?
Pia's robot draws a right triangle and forgets one label. It looks embarrassed. How long is that leg, in cm?
Ren draws a right triangle on a long poster with crayons. How long is the short leg, in inches?
Zee's pencil sketch shows a right triangle. The hypotenuse is not a whole number. Written as a square root, how long is it, in inches?
Ari's math book asks for an exact length, so no rounding today. Written as a square root, how long is the hypotenuse, in cm?
Bo builds a right triangle of tiles. The hypotenuse is not a whole number of inches. Written as a square root, how long is it?

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

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