\(L.H.S=\frac{cos({\pi}+x)cos(-x)}{sin({\pi}-x)cos(\frac{\pi}{2}+x)}\)
\(=\frac{[-cos\,x][cos\,x]}{(sin\,x)(-sin\,x)}\)
\(\frac{-cos^2x}{-sin^2x}\)
\(=cot^2x\)
\(=R.H.S.\)
Prove that. \(sin^2 \frac{π}{6}+cos^2 \frac{π}{3}–tan^2 \frac{π}{4}=-\frac{1}{2}\)
Find the mean and variance for the following frequency distribution.
Classes | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 |
Frequencies | 5 | 8 | 15 | 16 | 6 |