a) Find the value of $m$ if $\sec 65^{\circ}=\operatorname{cosec}(2 m-15)^{\circ}$
\(\boxed{m = 20}\)
Step 1 :Given that \(\sec 65^\circ = \operatorname{cosec}(2m - 15)^\circ\)
Step 2 :Using the identities \(\sec x = \frac{1}{\cos x}\) and \(\operatorname{cosec} x = \frac{1}{\sin x}\), we get \(\frac{1}{\cos 65^\circ} = \frac{1}{\sin (2m - 15)^\circ}\)
Step 3 :Using the identity \(\sin (2x) = 2 \sin x \cos x\), we can rewrite the equation as \(\frac{1}{\cos 65^\circ} = \frac{1}{2 \sin (m - 7.5^\circ) \cos (m - 7.5^\circ)}\)
Step 4 :Solving for m, we get \(m = 20\)
Step 5 :\(\boxed{m = 20}\)