SOLUTION: if sinA - cotA =0, find:- 1) angle A 2)1-tan^2A/1+tan^2A

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Question 772041: if sinA - cotA =0, find:-
1) angle A
2)1-tan^2A/1+tan^2A
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
if sinA - cotA =0, find:-
1) angle A
2)1-tan^2A/1+tan^2A
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sinA - cotA =0
sinA - cosA/sinA = 0
sin^2 - cos = 0
1-cos^2 - cos = 0
cos^2 + cos - 1 = 0
Sub x for cos(A)
x^2 + x - 1 = 0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation (in our case ) has the following solutons:



For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=5 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 0.618033988749895, -1.61803398874989. Here's your graph:

-----------------
A =~ 51.8273 degs


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