Angles of the triangle: ∠A=30° ∠B=60° ∠C=90°

Hypotenuse: 1 mulliken (10 inches)

How can I find the sin A, cos A, and tan A?

you should memorize the ratio of sides of the 30-6-90 right-angled triangle

30-60-90 ---> 1 √3 2
-----> 5 5√3 10

sinA = sin30 = 5/10 = 1/2
cosA = cos30 = 5√3/10 = √3/2
tanA = tan30 = 5/5√3 = 1/√3