ANSWER.
The measure of angle A is 53.13°.
STEP BY STEP
Given,
ABC is a triangle,
In which m∠CBA = 90°, AB = 3 cm, BC = 4 cm and CA = 5 cm,
By the law of sine,
( By cross multiplication )
By substituting the values,
( sin 90° = 1 )
Hence, the measure of angle A is 53.13°.