In a right-angled triangle, the leg is 9 cm and the cosine of the included angle is 0.3, find the second leg.

The cosine of the angle is the ratio of the adjacent leg to the hypotenuse. Find the hypotenuse, divide the leg length, equal to 9 cm, by the cosine.

s = 9 cm ÷ 0.3 = 30 cm.

Now we can find the second leg according to the Pythagorean theorem.

a = √ ((30 cm) ² – 9 cm) ²) = √819 cm² = 28.62 cm.

Answer: the second leg is 28.62 cm.