（1）cos60°-sin^2 45°+sin^2 45°+1/4tan^2 30°+cos30°-sin30°（2）sin30°/（sin60°-cos45°）-（根号下（1-tan60°）^2）-tan45°第一题是这个（1）cos60°-sin^2 45°+1/4tan^2 30°+cos30°-sin30°

sin^2 45°-cos60°+tan60°*cos30° 3|tan30°-1|+sin平方60°-（cos60°-1）负2次方*tan45°+tan60°=? （1）cos60°-sin^2 45°+sin^2 45°+1/4tan^2 30°+cos30°-sin30°（2）sin30°/（sin60°-cos45°）-（根号下（1-tan60°）^2）-tan45°第一题是这个（1）cos60°-sin^2 45°+1/4tan^2 30°+cos30°-sin30° sin²30°+根号2cos45°*cos60°-tan²45°... 1/4tan²45°+1/sin²30°-3cos²30°+tan45°/cos60°-sin60°/cos60° sin²60°-tan45°×cos60°-tan²60° 根号（cos60°-1）²+sin60°-1的绝对值急 sin²45°-cos60°- tan45°分之cos30° +2sin²60°乘tan60° 1)cos60°/sin60°-sin45°2)(1-tan60°)的绝对值+2sin²45°3)(cot60°-sin60°)/sin²45°×tan30°4)[根号（tan30°-cos30°）² ]+(cos60°-cot60°)的绝对值 证明(sinα)^2+(sin(120°-α))^2-2sinαsin（120°-α）cos60°=(sin60°)^2证明(sinα)^2+(sin(120°-α))^2-2sinαsin（120°-α）cos60°=(sin60°)^2 cos²45°-1/cos60°+1/tan45°+cos²30°+sin²45° cos60°÷si30°－tan45°+sin²45° 2*sin(60°-B)*sinB=cos(60°-2B)-cos60° sin平方45°-tan平方30°另外还有一道 2sin平方30°×tan30°+cos60°tan60° 为什么sin(60°+18°)-sin(60°-18°)= 2cos60°sin18° 计算：2(cos^2)45°—cos60° 2分之1cos60°-根号2sin45° sin10°sin50°为什么等于1/2(cos40-cos60) 计算：cos60°+2/根2-根8-1/2