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7th grade Can these sides and angles make a triangle? worksheet

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Can these sides and angles make a triangle?

Grade 7 Math Worksheet

NameDate

Circle the best answer.

  1. Luz lines up three paper strips that are 9 cm, 6 cm and 20 cm long. Which describes the triangles Luz can build with them as sides?

    • More than one triangle: different sizes or shapes fit
    • No triangle: nothing fits
    • Exactly one triangle: only one size and shape fits

  2. Milo has three pieces of yarn that are 15 cm, 7 cm and 8 cm long. Which describes the triangles Milo can build with them as sides?

    • More than one triangle: different sizes or shapes fit
    • No triangle: nothing fits
    • Exactly one triangle: only one size and shape fits

  3. Noah lays out three pencils that are 12 cm, 11 cm and 20 cm long. Which describes the triangles Noah can build with them as sides?

    • Exactly one triangle: only one size and shape fits
    • More than one triangle: different sizes or shapes fit
    • No triangle: nothing fits

  4. Ren wants to draw a kite wing with angles of 35°, 60° and 75°. Which describes the triangles Ren can draw?

    • Exactly one triangle: only one size and shape fits
    • More than one triangle: different sizes or shapes fit
    • No triangle: nothing fits

  5. Esme draws a side of 5 cm, then wants angles of 92° and 88° at its two ends. Which describes the triangles Esme can draw?

    • Exactly one triangle: only one size and shape fits
    • More than one triangle: different sizes or shapes fit
    • No triangle: nothing fits

  6. Kira knows two angles, 110° and 85°, and a 7 cm side that is not between them. Which describes the triangles Kira can draw?

    • No triangle: nothing fits
    • Exactly one triangle: only one size and shape fits
    • More than one triangle: different sizes or shapes fit

  7. Noah sketches two sides of 7 cm and 7 cm that meet at an angle of 100°. Which describes the triangles Noah can draw?

    • No triangle: nothing fits
    • More than one triangle: different sizes or shapes fit
    • Exactly one triangle: only one size and shape fits

  8. Ren sketches two sides of 6 cm and 11 cm that meet at an angle of 20°. Which describes the triangles Ren can draw?

    • Exactly one triangle: only one size and shape fits
    • No triangle: nothing fits
    • More than one triangle: different sizes or shapes fit

  9. Read this first

    Use this

    Table with three rows. Row A: angles 35°, 55° and 90°. Row B: sides 9 cm, 12 cm and 16 cm. Row C: angles 100° and 95° and the 7 cm side between them.

  10. Tala lists what three friends know about the triangle each wants to draw. Which row can build exactly one triangle?

    • Row C
    • Row A
    • Row B

  11. Use this

    Table with three rows. Row A: angles 55°, 60° and 65°. Row B: sides 10 cm, 13 cm and 18 cm. Row C: sides 5 cm, 6 cm and 15 cm.

  12. Bo lists what three friends know about the triangle each wants to draw. Which row can build exactly one triangle?

    • Row B
    • Row C
    • Row A
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7th grade Can these sides and angles make a triangle? worksheet – printable
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About this worksheet

Can these sides and angles make a triangle?. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can check three sides: the two shorter ones must add to more than the longest, and then they make exactly one triangle.
  • I can check angles: three angles that add to 180° make many triangles (a small one and a big one), and two angles plus a side make exactly one.
  • I can tell when two sides and an angle make one triangle (angle between them), none, or more than one (angle not between them).

Standard: 7.G.A.2

Words to know

side: One edge of a triangle. A length such as 8 cm tells how long it is.

angle: The opening at a corner, measured in degrees. A triangle's three angles add to 180°.

between: An angle is between two sides when those two sides meet at its corner.

unique: Only one triangle fits. Any other one is the same shape and size, turned or flipped.

more than one: Different triangles fit: the same angles can make a small and a big triangle.

close up: The ends meet, so the sides make a triangle. Short sides can't reach and close up.

swinging side: A side that turns from a fixed point like a compass arm, touching the base.

Common mistakes

Your child thought three angles that add to 180° make just one triangle. Draw a small triangle and a big one with the same three corners: the angles match, but the sizes do not.

Your child thought three side lengths can build more than one triangle. Try it with three straws: however you move them, the triangle comes out the same shape and size.

Your child did not check the angles against 180°.

What to say

Ask: what do the angles add to, and is there room for a triangle?

Questions parents ask

What is the most common mistake with can these sides and angles make a triangle??

Your child thought three angles that add to 180° make just one triangle. Draw a small triangle and a big one with the same three corners: the angles match, but the sizes do not.

Are these 7th 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 7 math

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