Question

计算：tan30°?sin60°+cos230°-sin245°?cos60°

计算：tan30°?sin60°+cos230°-sin245°?cos60°．

Answer 1

原式=

3

3

×

3

2

+(

3

2

)2-(

2

2

)2×

1

2

=

1

2

+

3

4

-

1

4

=1．