Why not we taken common angle

1. evaluate √-i

1. Why -cos y. Is equal to cos y in next step
   

The elevation of a tower of a station A due north of it is α and at a station B due west of A is β. Prove that the height of the tower is (AB sin⁡α  sin⁡β)/√(sin² ⁡α  -sin² ⁡β )

Place root 8.3 on number line - Chapter 1

Let set A = {x: x is a multiple of 3}, set B = {x: x is a multiple of 5}. Then A ∩ B is given by

Triangle AEC is right-angled at E, B is a point on EC, BD is the altitude of triangle ABC, AC = 25 cm, BC = 7 cm and AE = 15 cm. Find the area of triangle ABC and the length of DB.

Evaluate definite integral e^{cos x} / e^{cos x} + e^{-cos x} 0 to pi

Question number 2

tan 8 theta - tan 6 theta -tan 2 theta =tan 8 theta × tan 6 theta × tan 2 theta 

Example 14

I can't understnd  

Plzz will you make a video in this question

HOW TO DO WORKING OF GST

If x=costheta+sintheta ,y=costheta-sintheta then express it's value in terms of square of x +square of y

Sin18 degree, cos18 degree, sin 7 1/2, cos 7 1/2