Question

If cos A=3/5 and A is acute,find sin A,tan A,and sec A.

Answer 1

Use a2 + b2 = c2 of the right triangle to find the length of the missing side. c=hypotenuse which in this case is 5. 3^2 + b^2 = 5^2
9 + b^2=25
b^2=16
b=4

sin=opposite over hypotenuse which is 4/5
tan=opposite over adjacent which is 4/3
sec=the reciprocal of cosine which is 5/3 (just change the top and bottom numbers of cosine to get secant)