设f(t)连续并满足
f(t)=cos2t+∫
0
t
f(s)sinsds， (*)
求f(t)．
【正确答案】正确答案：因f(t)连续
∫
0
t
f(s)sinsds可导
f(t)可导．于是
∫
0
t
f(s)sinsds可导
f(t)可导．于是
【答案解析】
∫
0
t
f(s)sinsds可导
f(t)可导．于是