The three sides of a right-angled triangle have special names. The hypotenuse (\(h\)) is the longest side. It is opposite the right angle. The opposite side (\(o\)) is opposite the angle in question ( ...

The double angle formulae are: \(\sin 2A = 2\sin A\cos A\) \(\cos 2A = {\cos ^2}A - {\sin ^2}A\) \(= 2{\cos ^2}A - 1\) \(= 1 - 2{\sin ^2}A\) From the triangle below ...