Angles of a triangle: the sum and the exterior angle

Answer Key - Grade 8 Math Worksheet

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

1. 1.

   Pia looks at the side of a ramp, a right triangle. One of its other angles is 34°. How many degrees is the third angle?

   56
2. 2.

   Ren leans a ladder on a wall, making a right triangle with the ground. One of its other angles is 75°. How many degrees is the third angle?

   15
3. 3.

   Zee builds an isosceles roof frame. The top angle is 44°. How many degrees is each base angle?

   68
4. 4.

   Ari builds an isosceles tent frame. The top angle is 82°. How many degrees is each base angle?

   49
5. 5.

   Kira builds an isosceles sail frame. Each base angle is 38°. How many degrees is the top angle?

   104
6. 6.

   Milo draws triangle HQS and extends side HQ past corner Q. Angle H is 45° and angle S is 46°. How many degrees is the outside angle at Q?

   91
7. 7.

   Tala draws triangle SUV and extends side SU past corner U. The outside angle at U is 132° and angle S is 58°. How many degrees is angle V?

   74
8. 8.

   Bo draws triangle CDF and extends side CD past corner D. Angle C is 50° and angle F is 60°. Which equation finds x, the outside angle at D?

   • x = 180 − 50 − 60
   • x = 50 + 60
   • x = 60 − 50
9. 9.

   Jun draws triangle UVW and extends side UV past corner V. Angle U is 38° and angle W is 51°. Which equation finds x, the outside angle at V?

   • x = 51 − 38
   • x = 180 − 38 − 51
   • x = 38 + 51
10. 10.

    Kira draws triangle GHQ and extends side GH past corner H. Angle G is 64° and angle Q is 41°. Which equation finds x, the outside angle at H?

    • x = 64 − 41
    • x = 64 + 41
    • x = 180 − 64 − 41