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The Pythagorean Theorem: Grade 8 Math Worksheet – PDF Download

    The Pythagorean Theorem – Grade 8 math worksheet
    These 23 problems practice Common Core standards 8.G.B.6 and 8.G.B.7. Start with hypotenuses and missing legs, then explain the proof with areas, use the converse to test triangles, and finish with ladders, TV screens, ball fields and boxes in two and three dimensions. Show each step and round only at the end.
    Grade 8Common Core: 8.G.B.6 · 8.G.B.7

    Problem 1: Hypotenuse of a 6-8 triangle

    Find the length of the hypotenuse.

    6 in8 inc = ?
    Legs of 6 in and 8 in.

    Problem 2: Hypotenuse of a 5-12 triangle

    A right triangle has legs of 5 ft and 12 ft. Find the hypotenuse.

    Problem 3: Find the missing leg

    Find the missing leg.

    x = ?8 yd17 yd
    Hypotenuse 17 yd, one leg 8 yd.

    Problem 4: Missing leg of a 7-25 triangle

    The hypotenuse of a right triangle is 25 in. One leg is 7 in. Find the other leg.

    Problem 5: Legs 9 and 12

    Find the hypotenuse of a right triangle with legs 9 in and 12 in.

    Problem 6: Hypotenuse that is not whole

    A right triangle has legs of 4 ft and 7 ft. Find the hypotenuse. Give the exact value and then round to the nearest tenth.

    Problem 7: Leg that is not whole

    The hypotenuse of a right triangle is 13 in. One leg is 9 in. Find the other leg to the nearest tenth.

    Problem 8: Squares on the sides

    The squares built on the legs of a right triangle have areas 36 square units and 64 square units. Find the area of the square on the hypotenuse and the length of the hypotenuse.

    3664?
    Areas of the two leg squares are given.

    Problem 9: Area proof with numbers

    A square with side length 17 in. holds four congruent right triangles with legs 5 in. and 12 in. and a tilted square. (a) Find the area of the large square. (b) Find the total area of the four triangles. (c) Find the area of the tilted square. (d) Find its side length.

    512c
    Four triangles with legs 5 and 12 fill the corners.

    Problem 10: Explain the proof

    In the square-and-triangles figure, the large square has side \(a+b\) and the tilted square has side \(c\). Explain, using areas, why \(a^{2}+b^{2}=c^{2}\).

    Problem 11: Converse: 9, 12, 15

    A triangle has sides 9 in., 12 in. and 15 in. Is it a right triangle? Explain.

    Problem 12: Converse: 7, 10, 12

    A triangle has sides 7 ft, 10 ft and 12 ft. Is it a right triangle? Explain.

    Problem 13: Which sets are right triangles?

    Which of these side lengths form a right triangle? Show the check for each.

    1. 8, 15, 17
    2. 6, 7, 10
    3. 20, 21, 29
    4. 11, 12, 18

    Problem 14: Perimeter and area

    The legs of a right triangle measure 10 in. and 24 in. Find the perimeter and the area.

    Problem 15: Diagonal of a square

    A square picture frame is 9 in. on each side. Find the length of its diagonal to the nearest tenth.

    9 in9 ind = ?
    A diagonal splits the square into two right triangles.

    Problem 16: Height of an isosceles triangle

    An isosceles triangle has a base of 12 in. and two equal sides of 10 in. Find its height. Then find its area.

    12 in10 in10 inh = ?
    The height splits the base into two parts of 6 in.

    Problem 17: Diagonal of a prism

    A rectangular prism is 8 in. long, 6 in. wide and 24 in. tall. Find the length of the space diagonal, from a bottom corner to the opposite top corner.

    d = ?8 in6 in24 in
    Find the space diagonal.

    Problem 18: Ladder against a house

    A 25-ft ladder leans against a house. Its base is 7 ft from the wall. How high up the wall does the ladder reach?

    h = ?7 ft25 ft
    The ladder is the hypotenuse.

    Problem 19: TV screen diagonal

    A TV screen is 24 in. wide and 18 in. tall. TVs are sold by the length of the screen diagonal. What size is this TV?

    24 in18 ind = ?
    Screen width and height.

    Problem 20: Little League throw

    A Little League infield is a square with 60 ft between bases. The catcher at home plate throws to second base. How far is the throw to the nearest tenth of a foot?

    60 ft60 ftthrow
    Home plate is at the bottom left and second base is at the top right.

    Problem 21: Is the corner square?

    Sofia builds a rectangular door frame. She measures 60 in. along the bottom and 80 in. up the side. The diagonal between those two points measures 100 in. Is the corner a right angle? Explain.

    Problem 22: Walk east and north

    Jamal walks 0.9 mi east and then 1.2 mi north. How far is he from where he started, in a straight line?

    0.9 mi east1.2 mi northd = ?
    East and north make a right angle.

    Problem 23: Longest rod in a box

    A storage box is 12 in. long, 9 in. wide and 8 in. tall. Maya wants to store a straight rod that is 17 in. long. Will it fit inside the box? Explain.

    d12 in9 in8 in
    The longest straight rod lies along the space diagonal.

    The Pythagorean Theorem: Grade 8 worksheet answer key

    See every chapter on the Grade 8 math page.

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