Question

If sin θ=.55 what is the value of cos θ and explain why

Answer 1

Answer:

$cos(\theta)=(+/-)0.84$

Step-by-step explanation:

we know that

$sin^2(\theta)+cos^2(\theta)=1$ ----> by trigonometric identity

we have

$sin(\theta)=0.55$

substitute

$(0.55)^2+cos^2(\theta)=1$

$cos^2(\theta)=1-(0.55)^2$

$cos^2(\theta)=0.6975$

$cos(\theta)=(+/-)\sqrt{0.6975}$

$cos(\theta)=(+/-)0.84$

Remember that

If the sine of angle theta is positive, then the angle theta lie on the I Quadrant or II Quadrant

therefore

If the angle theta is on the I Quadrant the cosine  will be positive

If the angle theta is on the II Quadrant the cosine  will be negative