Question

cos90degrees cos30 degrees + sec-squared45degrees sin30degrees - cos270degrees sin180degrees

Answer 1

Step-by-step explanation:

$\cos 90 \cos 30 + \sec^2 45 \sin 30 - \cos 270 \sin 180$

But we know that

$\cos 90 = \cos 270 = \sin 180 = 0$

and

$\sin 30 = \dfrac{\sqrt{3}}{2} \:\:\text{and}\:\: \sec 45 = \sqrt{2}$

so this leaves us with just

$\sec^2 45 \sin 30 = (\sqrt{2})^2 \left(\dfrac{\sqrt{3}}{2} \right)= \sqrt{3}$