设函数 f ( x )对所有的实数 x 都满足 f ( x+ 2 π ) =f ( x ),求证:存在4个函数 f i ( x )( i =1,2,3,4)满足:(1)对 i =1,2,3,4, f i ( x )是偶函数,且对任意的实数 x ,有 f i ( x+π ) =f i ( x );(2)对任意的实数 x ,有 f ( x ) =f 1 ( x ) +f 2 ( x )cos x+f 3 ( x )sin x+f 4 ( x )sin2 x 。
【简答题】用括号内所给单词的适当形式填空。 1. Blue Cat is enjoyed by ______(thousand) of children in China. 2. My father gives me a present in the box, I can’t wait ______ (open) it. 3. The birth of a baby panda in the zoo was...