Angles and sides of triangles

Answer Key - Grade 6 Math Worksheet

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

1. 1.

   Esme sketches a flower bed, a triangle with angles of 55° and 65°. What is the size of its third angle, in degrees?

   60
2. 2.

   Luz sketches a kite wing, a triangle with angles of 72° and 41°. What is the size of its third angle, in degrees?

   67
3. 3.

   Milo sketches a ramp as a right triangle. One of its other angles is 24°. What is the third angle, in degrees?

   66
4. 4.

   Tala cuts three straws to stand in a water glass. They are 13 cm, 6 cm and 7 cm long. Can the three straws make a triangle?

   • No: the two shorter straws together (13 cm) are not longer than the longest (13 cm)
   • No: a triangle needs all three straws the same length
   • Yes: the two shorter straws reach 13 cm, as far as the longest, so they fit and a triangle forms
5. 5.

   Zee cuts three straws to stand in a water glass. They are 14 cm, 9 cm and 7 cm long. Can the three straws make a triangle?

   • No: a triangle needs two straws of the same length, and these straws differ in length
   • No: the straws are all different lengths
   • Yes: the two shorter straws together (16 cm) are longer than the longest (14 cm)
6. 6.

   Ari cuts three straws to stand in a water glass. They are 18 cm, 5 cm and 8 cm long. Can the three straws make a triangle?

   • No: a triangle needs all three straws the same length
   • No: the two shorter straws together (13 cm) are not longer than the longest (18 cm)
   • Yes: any three straws make a triangle

7. Read this first

   Three sets of straws shown as bars on a number line in cm, ticks every 1 cm

   The lengths in each set are the ones listed in the choices.

8. 7.

   Esme sorts straws into three sets next to a water glass. Which set can make a triangle?

   • 2 cm, 3 cm and 8 cm
   • 4 cm, 5 cm and 9 cm
   • 6 cm, 7 cm and 10 cm
9. 8.

   Jun sorts straws into three sets next to a water glass. Which set can make a triangle?

   • 8 cm, 9 cm and 12 cm
   • 3 cm, 5 cm and 13 cm
   • 5 cm, 6 cm and 11 cm
10. 9.

    Tala draws triangle PQR on a map. Side QR is 6 cm, side RP is 8 cm and side PQ is 11 cm. Which corner has the largest angle?

    • Corner Q, at one end of the 11 cm side
    • Corner R, across from the 11 cm side
    • Corner P, at one end of the 11 cm side
11. 10.

    Zee draws triangle PQR on a map. Side QR is 12 cm, side RP is 7 cm and side PQ is 9 cm. Which corner has the largest angle?

    • Corner R, at one end of the 12 cm side
    • Corner P, across from the 12 cm side
    • Corner Q, at one end of the 12 cm side