(1)sin^2*30度-cos^2*30度+sin^2*45度 (2)2sin*45度/2cos30度-1

问题描述:

(1)sin^2*30度-cos^2*30度+sin^2*45度 (2)2sin*45度/2cos30度-1

(1)sin^2*30度-cos^2*30度+sin^2*45度
=(0.5)²-(√3/2)²+(√2/2)²
=1/4-3/4+1/2
=0
(2)2sin*45度/2cos30度-1
=2*(√2/2)/2(√3/2)-1
=√2/(√3-1)
=√2(√3+1)/2