Răspuns:
Explicație pas cu pas:
1
cos150°=-cos30°
√3/2+2×1/2-√3/2=1
2
cos135°=cos(180°-45°)=-cos45°
sin 135°=sin 35°
cos 135°+sin 135°=sin 35°-co45°=√2/2-√2/2=0
3
1/√3 cos30°-cos²45°=1/√3×√3/2-1/2=1/2-1/2=0
4
(sinx-cosx)²=sin²x+2sinxcosx+cos²x=1+sin2x=1-1=0
5
tgx=sinx/cosx
sinx=√1-4/9=√5/3
tgx=√5/3×3/2=√5/2
6
(sinx+3cosx)/cosx=4
cosx(sinx/cosx+3)/cosx=4 tgx+3=4 tgx=1 x=45°
