In triangle ABC, angle C is 90 °, BC = 4, sin A = 0.2. Find AB.

A right-angled triangle is a triangle in which the legs form a right angle of 90 °, and the legs are connected by the hypotenuse. The sine of the angle in a right-angled triangle is equal to the ratio of the opposite leg to the hypotenuse. We know the leg BC sine of angle A:

BC = 4;

sin A = 0.2;

Let’s make the proportion and find the hypotenuse AB:

sin A = opposite leg / hypotenuse = BC / AB = 0.2;

BC / AB = 2/10;

4 / AB = 2/10;

2 * AB = 40;

AB = 40/2;

AB = 20 – hypotenuse.

Answer: 20