Question

Given the triangle below, what is m
A. 46.2
B. 41.40
C. 48.4
D. 38.6°

Answer 1

B 41.4

Explanation:

complete Pythagoras for general triangles :

c² = a² + b² - 2ab×cos(C)

with "c" being the side opposite of the angle C.

=>

8² = 10² + 12² - 2×10×12×cos(C)

64 = 244 - 240×cos(C)

240×cos(C) = 244 - 64 = 180

cos(C) = 180/240 = 18/24 = 3/4 = 0.75

C = 41.40962211... ≈ 41.4