Question

In ΔABC, a = 1.9 inches, b = 7.1 inches and c=7.4 inches. Find the measure of ∠B to the nearest degree.

Answer 1

• 74°

Explanation:

Given ΔABC with:

• a = 1.9 in, b = 7.1 in, c=7.4 in

To find

• ∠B

Solution

Use the law of cosines

• cos B = (a² + c² - b²)/(2ac)
• cos B = (1.9² + 7.4² - 7.1²)/(2*1.9*7.4)
• cos B = 0.283
• m∠B = accos (0.283)
• m∠B = 74° (rounded)