1+sina=(?)^2

1=sina/2^2+cosa/2^2
sina=2sina/2*cosa/2

1-sina
=1-2sin(a/2)cos(a/2)
=(sin(a/2))^2-2sin(a/2)cos(a/2+=(cos(a/2))^2
=(sin(a/2)-cos(a/2))^2
1+sina=(?)^2同理
=(sin(a/2)+cos(a/2))^2

我刚开始还以为你耍宝呢
1+ 新浪？？？？？

原来是sin a

1= sin2 a+ cos2 a

原式= sin2 a - sin a +1 + cos2 a -1
= (sin a + 1)^2 + ....

1+sina=[sin(a/2)]^2+[cos(a/2)]^2+2[sin(a/2)][cos(a/2)]=[sin(a/2)+cos(a/2)]^2
同理1-sina=[sin(a/2)-cos(a/2)]^2

1=sina/2^2+cosa/2^2
sina=2sina/2*cosa/2
所以1+sina=(sia/2+cosa/2)^2

sia/2+cosa/2)^2