Let A be an acute angle such that sin 4A = sin 5A. What is the smallest possible measure of A in degrees?
I'm gonna correct your question first:
Your question: Let A be an acute angle such that sin 4A = sin 5A. What is the smallest possible measure of A in degrees?
Corrected question: Let A be an acute angle such that sin 4A = cos 5A. What is the smallest possible measure of A in degrees?
Angle A = 90 / (4 + 5) ==> ∠A = 10º
Proof:
sin 4A = sin 40º
sin 40º = cos 50º
cos 5A = cos 50º
