Question

if (1+cosA)(1-cosA)=3÷4 find value of sec A

Answer 1

1-(cosA)^2=3/4
1-3/4=(cosA)^2
1/4=(cosA)^2
1/2=cosA
1/2=1/secA
secA=2

Answer 2

The answer is 2

Please refer the above photograph for the used process.


KEY POINTS TO REMEMBER :-

1) (a+b) (a-b) = a² - b²

2) sin²A +cos²A = 1
So,
on Simplifying, we get :-
1 - cos²A = sin²A

3) secA = 1 / cosA

4) Values of the standard trigonometric angles like 0,30,45,60,90 degrees.
In this case the requirement is of 60°
So,
sin60° = root3 / 2
cos60° = 1 / 2


The problem is from the chapter of TRIGONOMETRY.
The basic idea of trigonometry is involved in the above question.
Please check out the attachment for the answer.


Thanks!