Question

Find the measure of Angle A. (include and explanation so I could do the rest on my own, preferably :)

Answer 1

Answer:

13) Angle A is 30°

14) Angle A is 45°

15) Angle A is 40°

16) Angle A is 40.5°

Step-by-step explanation:

By the angle sum theorem for the interior angles of a triangle, we have;

13) 130° + 2·x + 3·x = 180°

∴ 2·x + 3·x = 180° - 130° = 50°

2·x + 3·x = 5·x = 50°

x = 50°/5 = 10°

∠A = 3·x = 3 × 10° = 30°

∠A = 30°

14) 3·x + 9 + 4·x + 9 + 78° = 180°

7·x + 18 + 78° = 180°

7·x = 180° - (18 + 78)° = 180° - 96° = 84°

x = 84°/7 = 12°

∠A = 3·x + 9 = 3 × 12° + 9 = 45°

∠A = 45°

15) 90° + x + 51 + x + 61 = 180°

∴ x + 51 + x + 61 = 180° - 90° = 90°

2·x + 112 = 90°

2·x = (90 - 112)° = -22°

x = -22°/2 = -11°

x = -11°

∠A = x + 51 = -11° + 51 = 40°

∠A = 40°

16) x + 79 + x + 49 + 70° = 180°

x + x  = (180 - 70 - 79 - 48)° = -17°

2·x = -17°

x = -17°/2 = -8.5°

x = -8.5°

∠A = x + 49 = (-8.5 + 49)° = 40.5°

∠A = 40.5°.