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.
Bo measures a paper triangle. Two of its angles are 53° and 39°. The sketch writes 180° beside the triangle. What is the third angle?
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?
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?
Kira draws triangle CDF and extends side CD past corner D. The inside angle at D is 64°. The sketch writes 180° along the straight line. How many degrees is the outside angle at D?
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?
Pia draws triangle SUV and extends side SU past corner U. Angle S is 42° and angle V is 58°. How many degrees is the outside angle at U?
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?
Ari cuts three copies of a 50°-60°-70° triangle and puts the three different corners side by side along a ruler. What do the three corners make together?
- A straight line: 180°
- A square corner: 90°
- A full turn around a point: 360°
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?
Use the picture in question 8.
- A square corner: 90°
- A full circle around one point: 360°
- A straight line: 180°
Jun cuts three copies of a 40°-70°-70° triangle and puts the three different corners side by side along a ruler. What do the three corners make together?
Use the picture in question 8.
- A square corner: 90°
- A full turn: 360°
- A straight line: 180°