Question

Find the measure of

Answer 1

Answer:

∠ ABC ≈ 137.9°

Step-by-step explanation:

Using the Cosine rule in Δ ABC

cos B = $\frac{a^2+c^2-b^2}{2ac}$

with a = 89, b = 144, c = 65

cos B = $\frac{89^2+65^2-144^2}{2(89)(65)}$ = $\frac{7921+4225-20736}{11570}$ = $\frac{-8590}{11570}$ , thus

B = $cos^{-1}$ ( - $\frac{8590}{11570}$ ) ≈ 137.9° ( to the nearest tenth )