求值log(2)sin(3П/8)-log(1/2)sin(П/8)=? 注;2和1/2是底数

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/03 17:53:14
求值log(2)sin(3П/8)-log(1/2)sin(П/8)=? 注;2和1/2是底数

求值log(2)sin(3П/8)-log(1/2)sin(П/8)=? 注;2和1/2是底数
求值log(2)sin(3П/8)-log(1/2)sin(П/8)=? 注;2和1/2是底数

求值log(2)sin(3П/8)-log(1/2)sin(П/8)=? 注;2和1/2是底数
利用对数的运算法则和对数的性质即可
log(a)(b)=-log(1/a) (b)
logaM+loga N=loga (MN)
log(2)sin(3П/8)-log(1/2)sin(П/8)
=log(2)sin(3П/8)+log(2)sin(П/8)
=log(2) (sin(3П/8)*sin(П/8))
=log(2) (cos(П/8)*sin(П/8))
=log(2) (1/2)sin(π/4)
=log2(1/2)+log(2) sin(π/4)
=-1+log2( √2/2)
=-1-1/2
=-3/2

log(2)sin(3П/8)-log(1/2)sin(П/8)
=log(2)sin(3π/8)+log(2)sin(π/8)
=log(2)[sin(3π/8)sin(π/8)]
=log(2)[sin(3π/8)cos(3π/8)]
=log(2)[(1/2)sin(3π/4)]
=log(2)[(1/2)*(√2/2)]
=log(2)(√2/4)
=log(2)[2^(-3/2)]
=-3/2

原式=log2sin3/8π+log2sinπ/8
=log2 sin3/8πsinπ/8
=log2 sin3/8πcos3/8π
=log2 1/2sin3/4π
=log2 1/2 * 根号2/2
=log2 根号2/4
=1/2-2
= - 3/2