Explicație pas cu pas:
sin60°-cos30°=sin60°-cos(90°-60°)=sin60°-sin60°=0
sin20°-cos70°=sin20°-cos(90°-20°)=sin20°-sin20°=0
sin²130°+cos²50°=sin²(180°-50°)+cos²50°=sin²50°+cos²50°=1
sin²150°+cos²30°=sin²(180°-30°)+cos²30°=sin²30°+cos²30°=1
cos145°+cos35°=2*cos(145°+35°)/2*cos(145°-35°)/2=2*cos90°*cos55°=0
√3*sin60°-√2*cos45°=√3*√3/2-√2*√2/2=(3-2)/2=1/2
cos²45°+sin²135°=cos²45°+sin²(180°-45°)=cos²45°+sin²45°=1
sin²80°+sin²10°=sin²(90°-10°)+sin²10°=cos²10°+sin²10°=1
Bafta!!!!
