Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If $\sin \theta - \cos \theta = 0, 0^\circ < \theta < 90^\circ$, then the value of $\sin^4 \theta + \cos^4 \theta$ is:

Options:

$\frac{1}{3}$

1

$\frac{1}{2}$

$\frac{1}{4}$

Correct Answer:

$\frac{1}{2}$

Explanation:

Provided:-

sinθ - cosθ = 0

sinθ = cosθ

{ we know that if sinA = cosB  then A + B = 90º }

So, θ + θ  = 90º

θ  = 45º

Now,

sin4θ + cos4θ

= sin445º + cos445º

= (\(\frac{1}{√2}\))4 + (\(\frac{1}{√2}\))4

= \(\frac{1}{2}\)