求证1+sin a+cos a+2sin acos a/1+sin a+cos a=sin a+cos a
2个回答

sin a + cos a + (2sin acos a + 1) = sin a + cos a +(2sin acos a + (sin a)的平方 + ( cos a)的平方 )= (sin a + cos a)+ (sin a + cos a)的平方 = (sin a + cos a)(1+sin a+cos a)

上式除以 1+sin a+cos a=sin a+cos a