1.5 multiply 1.25

The tangent at any point of a circle is perpendicular to the radius through the point of contact 

This is theorem please prove?????? 

How we can prove the pythagoras theoram? 

Exercise 5.7 question 14 class 12th

Cos2x cosx/2 -cos3x cos9x/2 =sin7x/2 sin4x

Prove it

Plzz solve this:

Prove that:  tanA/1-cotA   +    cot/1-tanA   =  

1   +   tanA    +    cotA 

Find sum of first n terms of series 3 + 7 + 13 + 21 + 31 ...

Find the sum of n terms of series 3.8+6.11+9.14+...