Use the following figure not drawn to scale When an exercise

Use the following figure (not drawn to scale). When an exercise requests that you evaluate an angle, give answers in both radians and degrees. Suppose a = 4, b = 6, and c = 7. Evaluate: B

Solution

b² = a² + c² - 2ac cosB

36 = 16 + 49 - 56cosB

cosB = 29/56

B = 58.81 degree = 1.02645 radian