In ΔABC, a = 660 cm, b = 680 cm and c=100 cm. Find the measure of ∠B to the nearest degree.

m∠B = .

Step-by-step explanation:

Since the three sides of the triangle are given, then we apply cosine rule.

= + - 2ac Cos B

But, a = 660 cm, b = 680 cm, and c = 100 cm.

So that;

= + -2(660 x 100) Cos B

462400 = 435600 + 10000 - 132000 Cos B

462400 = 445600 - 132000 Cos B

132000 Cos B = 445600 - 462400

                        = -16800

Cos B =

         = -0.1273

B = -0.1273

  =

Thus, measure of ∠B is .

c

step-by-step explanation: