Question

不查表求值/(sin70°√1+cos40°)谢谢,要过程的!~

Answer 1

分子=cos40°+2*sin50°(cos10°*sin30°+cos30°*sin10°)/cos10°

=cos40°+2*cos40°*sin40°/cos10°

=cos40°+sin80°/cos10°

=2*(cos20°)^2-1+1

=2*(cos20°)^2

分母=sin70°*根号中(2*(1+cos40°)/2)

=sin70°*cos20°*根号2

=根号2*(cos20°)^2

所以值为根号2