- 高一数学暑假作业求值：1/2(csc10)
- 求值：1/2(c10)-2sin70
- 我试一下
1/2(csc10)-2sin70
=[1/(2sin10)]-2sin70
=[1-4sin10*sin70]/[/(2sin10)]
={1+2[cos(10+70)-cos(10-70)]}/[(2sin10)]
=[1+2(cos80-cos60)]/[(2sin10)]
=[1+2(cos80-0.5)]/[(2sin10)]
=(1+2cos80-1)/[(2sin10)]
=2cos80/[(2sin10)]
=1