Answer:
Option A- 60°
Step-by-step explanation:
Given : Function - [tex]4cos^2x-1=0[/tex]
To solve the function
Step 1 - Write the function
[tex]4cos^2x-1=0[/tex]
Step 2- Add 1 both side
[tex]4cos^2x=1[/tex]
Step 3- Divide 4 both side
[tex]cos^2x=\frac{1}{4}[/tex]
Step 4 - Taking root both side
[tex]cosx=\sqrt{\frac{1}{4}}[/tex]
Step 5 - solve
[tex]cosx=\pm{\frac{1}{2}}[/tex]
Either [tex]cosx={\frac{1}{2}}[/tex] or [tex]cosx=-{\frac{1}{2}}[/tex]
When [tex]cosx={\frac{1}{2}}[/tex]
[tex]\rightarrow cosx={cos\frac{\pi}{3}}[/tex]
[tex]\rightarrow x={\frac{\pi}{3}} or 60^{\circ}[/tex]
or when [tex]cosx=-{\frac{1}{2}}[/tex]
[tex]\rightarrow cosx={cos(\pi-\frac{\pi}{3})}[/tex]
[tex]\rightarrow x={\frac{2\pi}{3}} or 120^{\circ}[/tex]
Therefore, Option A is correct solution of function is at 60°.
