Jika sin70°=r\sin70\degree=rsin70°=r dan cos70°=s\cos70\degree=scos70°=s maka nilai dari cos110°.tan110°−cos250°=....\cos110\degree.\tan110\degree-\cos250\degree=....cos110°.tan110°−cos250°=....
r+sr+sr+s
r−sr-sr−s
12r+s\frac{1}{2}r+s21r+s
12r−s\frac{1}{2}r-s21r−s
s−rs-rs−r