Question

Trigonometric Equation

2cos^2A - cosA = 0

Answer 1

factor cos A
cos A (2cosA -1)=0
or use substitution cos A = x
so 2x^2-x=0

Answer 2

Then what? @amoodarya

Answer 3

@Callisto

Answer 4

Do you know how to solve a quadratic equation?

Answer 5

Yes. But i dont know how to do this?

Answer 6

Let x = cosA
2cos^2A - cosA = 0 is then rewritten as
2x^2 - x = 0

First, solve for x. What do you get?

Answer 7

I got:
x(2x-1)

Which will be x=0, x=1/2

Answer 8

Substitute x=cosA again into the solutions you got, i.e.
cosA = 0 or cosA = 1/2
Can you solve A now?

Answer 9

What formula shall i use?
I'm really sorry i' new to this

Answer 10

Wait let me try

Answer 11

You need not use formula. Just a table and a graph.

Answer 12

Isee

Cos A=0
A={0,180}

Cos A=1/2
A={60,300}

Did i do it correctly???