因式分解①、 ②.
(本题6分) (1)已知:sinα·cos60º=,求锐角α; (2)计算:.
(1)(配方法) (2) (3) (4)()()—
计算:.
(每小题5分,本题共20分)计算:(1) (2)(-+-)×(-48)(3)(4)
(本题6分)(1)已知:sinα·cos60°=,求锐角α.(2)计算:.