Angles and sides of triangles

Answer Key - Grade 6 Math Worksheet

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

1. 1.

   Jun sketches a tent end, a triangle with angles of 30° and 100°. What is the size of its third angle, in degrees?

   50
2. 2.

   Kira sketches a boat sail, a triangle with angles of 48° and 62°. What is the size of its third angle, in degrees?

   70
3. 3.

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

   67
4. 4.

   Noah sketches a sled ramp as a right triangle. One of its other angles is 38°. What is the third angle, in degrees?

   52
5. 5.

   Pia sketches a ladder against a wall as a right triangle. One of its other angles is 62°. What is the third angle, in degrees?

   28
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?

   • Yes: any three straws make a triangle
   • No: the two shorter straws together (13 cm) are not longer than the longest (18 cm)
   • No: a triangle needs all three straws the same length
7. 7.

   Bo cuts three straws to stand in a water glass. They are 12 cm, 5 cm and 7 cm long. Can the three straws make a triangle?

   • No: a triangle needs all three straws the same length
   • Yes: the two shorter straws reach 12 cm, as far as the longest, so they fit and a triangle forms
   • No: the two shorter straws together (12 cm) are not longer than the longest (12 cm)

8. 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.

9. 8.

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

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

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

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

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

    • 7 cm, 10 cm and 14 cm
    • 6 cm, 9 cm and 15 cm
    • 4 cm, 5 cm and 12 cm