Question

计算：①tan60°cos30°-sin30°tan45°②sin30°?cos245°+34tan260°+sin260°

计算：①tan60°cos30°-sin30°tan45°②sin30°?cos245°+34tan260°+sin260°．

Answer 1

①原式=

3

×

3

2

-

1

2

×1
=

3

2

-

1

2

=1；

②原式=

1

2

-（

2

2

）²+

3

4×( 3 )2

+（

3

2

）²
=

1

2

-

1

2

+

1

4

+

3

4

=1．