In triangle ABC, angle C is 90 °, AC is 3, sinA is 3/5. Find BC.

Since the angle C is 90 degrees, the triangle is right-angled. Opposite the right angle in the rectangle lies the hypotenuse AC, which is 3 centimeters. Knowing that the sine of angle A is 3/5, we can calculate the side that lies opposite this angle. The sine of the angle is equal to the ratio of the opposite leg to the hypotenuse. Opposite corner A lies leg BC.
sine A = BC / AC;
Substitute the values of sine A and hypotenuse, calculate the length of the leg BC.
3/5 = BC / 3;
BC = 3/5 * 3 = 9/5 = 1.8 centimeters.
Answer: 1.8 centimeters.