How to use a definite integral to find area(2)

<正>Another example,the sine and cosine curves intersect fromx=π/4to x=5π/4.However,we want to find the area of the region bounded by the sine and cosine curves fromx=0to x=2π.Analysis:Let f(x)=sinx,and g(x)=cosx.Let f(x)=g(x),and find xin sinx=cosxas x∈[0,2π]x=π/4 or x=5π/4.