Question

计算：
①sin45°-cos45°+tan30°                
②

2sin60°+1

2cos30°- 2 sin45°

．

Answer 1

①原式=

2

2

-

2

2

+

3

3

=

3

3

；

②原式=

2× 3 2 +1

2× 3 2 - 2 × 2 2

=

3 +1

3 -1

=

( 3 +1)( 3 +1)

( 3 -1)( 3 +1)

=

4+2 3

2

=2+

3

．