Question #17bd1

1 Answer
Jul 8, 2016

See.the explanation, for proof.

Explanation:

Let I be the definite integral and #x =pi-t#. The limits become #pi#

and 0, and dx = #-dt#. .

Now, #I=-int(pi-t)f(sin(pi-t)) dt#, from #t= pi# to t = 0.

#=pi int f(sin t) dt-int t f(sin t) dt#, from t = 0 to #pi#,

using #sin (pi-t)=sin t#,

#=pi int f(sin x) dx#, from x = o to x =# pi -I#.

Thus,# I = pi/2 int f(sin x) dx#, from x = 0 to x =# pi#.