tolong dong matematika minat identitas trigonometri sma kls 11

Identitas Trigonometri.

Nomor 4
[tex]\displaystyle \cos b+\sin b\tan b\\ =\cos b+\sin b~\frac{\sin b}{\cos b}\\ =\frac{\cos^2 b+\sin^2 b}{\cos b}\\ =\frac{1}{\cos b}\\ =\sec b[/tex]
Terbukti.

Nomor 5
[tex]\displaystyle \frac{1+\tan^2 A}{2\tan A}\\ =\frac{1+\left ( \frac{\sin A}{\cos A} \right )^2}{2\frac{\sin A}{\cos A}}\\ =\frac{\frac{\cos^2 A+\sin^2 A}{\cos^2 A}}{\frac{2\sin A}{\cos A}}\\ =\frac{\cos^2 A+\sin^2 A}{2\cos A \sin A}\\ =\frac{1}{\sin 2A}\\ =\csc 2A[/tex]