(a) If n > 2 is an integer, show thaty sinnx dx − 2 1

n cos x sinn21x 1 n 2 1 n y sinn22x dx This is called a reduction formula because the exponent n has been reduced to n 2 1 and n 2 2.

(b) Use the reduction formula in part

(a) to show that

(c) Use parts

(a) and

(b) to evaluate y sin4x dx.

28.

(a) Prove the reduction formula

(b) Use part

(a) to evaluate y cos2x dx.

(c) Use parts

(a) and

(b) to evaluate y cos4x dx.

sinx dx = *2 sin 2x + C 4