In a right-angled triangle ABC, the angle C is 90 degrees, the angle B is 60 AB = 12cm. Find BC.

In the problem, a right-angled triangle is given, in which AB is the hypotenuse, one of the acute angles B is 60 °, you need to find BC.

Leg BC – adjacent to corner B, we will use the trigonometric function cos.

Cos B is the ratio of the leg of the adjacent angle to the hypotenuse:

Cos B = BC: AB.

Let’s solve the resulting equation for the aircraft:

BC = AB × cos B.

Substitute the values AB = 12 cm, cos B = cos 60 ° = 1/2 and find BC.

BC = 12 x 1/2;

BC = 12: 2;

BC = 6 cm.