Question
 Prove that:
$2\sin^2\frac{3\pi}{4}+2\cos^2\frac{\pi}{4}+2\sec^2\frac{\pi}{3}=10$

Answer

L.H.S =

$2\sin^2\frac{3\pi}{4}+2\cos^2\frac{\pi}{4}+2\sec^2\frac{\pi}{3}$

$=2\Big\{\sin\Big(\pi-\frac{\pi}{4}\Big)\Big\}^2+2\Big(\frac{1}{\sqrt{2}}\Big)^2+2(2)^2$

$=2\Big\{\sin\frac{\pi}{4}\Big\}^2+2\times\frac{1}{2}+8$

$=2\Big(\frac{1}{\sqrt{2}}\Big)^2+1+8$

$=1+1+8$

$=10$

= R.H.S.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Sketch the graphs of the following trigonometric functions:
$\text{h(x)}=\cos^22\text{x}$
IQ of a person is given by the formula
$\mathrm{IQ}=\frac{\mathrm{MA}}{\mathrm{CA}} \times 100$
where MA is mental age and CA is chronological age. If 80 $\le$ IQ $\le$ 140 for a group of 12 years old children, find the range of their mental age.
Solve the following equations:
$\sin\text{x}+\sin2\text{x}+\sin3\text{x}+\sin4\text{x}=0$
Find the value of the expression
$3[\sin^4\Big(\frac{3\pi}{2}-\alpha\Big)+\sin^4(3\pi+\alpha)]-2[\sin^6\Big(\frac{\pi}{2}+\alpha\Big)+\sin^6(5\pi-\alpha)]$
Find the maximum and minimum values of each of the following trigonometrical expressions:
$\sin\text{x}-\cos\text{x}+1$
Find the equation of the straight line perpendicular to 2x - 3y = 5 and cutting off an intercept 1 on the positive direction of the x-axis.
Prove the following by the principle of mathematical induction:
52n+2 + 24n - 25 is divisible by 576 for all $\text{n}\in\text{N}$
How many words can be formed with the letters of the word 'UNIVERSITY', the vowels remaining together?
A man accepts a position with an initial salary of ₹ 5200 per month. It is understood that he will receive an automatic increase of ₹ 320 in the very next month and each month thereafter.
  1. Find his salary for the tenth month.
  2. What is his total earnings during the first year?
Let r and n be positive integers such that 1 < r < n. Then prove the following:
$\frac{{{^\text{n}}\text{C}_{\text{r}}}}{{^\text{n-1}}\text{C}_{\text{r}-1}}=\frac{\text{n}}{\text{r}}$