8th grade Angles of a triangle: the sum and the exterior angle worksheet

Angles of a triangle: the sum and the exterior angle

Grade 8 Math Worksheet - Building Confidence

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

1. 1.

   Ari measures a triangular sail. Two of its angles are 47° and 68°. The sketch writes 180° beside the triangle. What is the third angle?
2. 2.

   Esme measures a triangular tent flap. Two of its angles are 35° and 73°. The sketch writes 180° beside the triangle. What is the third angle?
3. 3.

   Jun measures a triangular kite wing. Two of its angles are 62° and 64°. The sketch writes 180° beside the triangle. What is the third angle?
4. 4.

   Luz draws triangle GHQ and extends side GH past corner H. The inside angle at H is 38°. The sketch writes 180° along the straight line. How many degrees is the outside angle at H?
5. 5.

   Milo draws triangle SUV and extends side SU past corner U. The inside angle at U is 71°. The sketch writes 180° along the straight line. How many degrees is the outside angle at U?
6. 6.

   Noah draws triangle WYC and extends side WY past corner Y. The inside angle at Y is 85°. The sketch writes 180° along the straight line. How many degrees is the outside angle at Y?
7. 7.

   Ren draws triangle WYC and extends side WY past corner Y. Angle W is 36° and angle C is 49°. How many degrees is the outside angle at Y?
8. 8.

   Tala draws triangle DFG and extends side DF past corner F. Angle D is 57° and angle G is 29°. How many degrees is the outside angle at F?
9. 9.

   Zee draws triangle HQS and extends side HQ past corner Q. Angle H is 44° and angle S is 71°. How many degrees is the outside angle at Q?
10. 10.

    Esme cuts three copies of a 30°-40°-110° triangle and puts the three different corners side by side along a ruler. What do the three corners make together?

    • A full circle around one point: 360°
    • A square corner: 90°
    • A straight line: 180°