If cos Θ = square root 2 over 2 and 3 pi over 2 < Θ < 2π, what are the values of sin Θ and tan Θ?

Verified Answer :

For the answer to the question above, If cos Θ = square root 2 over 2 and 3 pi over 2 < Θ < 2π, what are the values of sin Θ and tan Θ? 

If 3 pi over 2 < Θ < 2π Then the signs of sinx and tanx are both negative. 

cos(x) = sqrt(2)/2. So sin(x) = -sqrt(2)/2 and tan(x) = -1. 

sin Θ = square root 2 over 2; tan Θ = −1 

sin Θ = negative square root 2 over 2; tan Θ = 1 

sin Θ = square root 2 over 2; tan Θ = negative square root 2 

sin Θ = negative square root 2 over 2; tan Θ = −1

Answer:

The answer is

\(sin(\theta)=-\frac{\sqrt{2}}{2}\)

\(tan(\theta)=-1\)

Step-by-step explanation:

we know that

\(tan(\theta)=\frac{sin(\theta)}{cos(\theta)}\)

\(sin^{2}(\theta)+cos^{2}(\theta)=1\)

In this problem we have

\(cos(\theta)=\frac{\sqrt{2}}{2}\)

\(\frac{3\pi}{2} <\theta < 2\pi\)

so

The angle \(\theta\) belong to the third or fourth quadrant

The value of \(sin(\theta)\) is negative

Step 1

Find the value of  \(sin(\theta)\)

Remember

\(sin^{2}(\theta)+cos^{2}(\theta)=1\)

we have

\(cos(\theta)=\frac{\sqrt{2}}{2}\)

substitute

\(sin^{2}(\theta)+(\frac{\sqrt{2}}{2})^{2}=1\)

\(sin^{2}(\theta)=1-\frac{1}{2}\)

\(sin^{2}(\theta)=\frac{1}{2}\)

\(sin(\theta)=-\frac{\sqrt{2}}{2}\) ------> remember that the value is negative

Step 2

Find the value of \(tan(\theta)\)

\(tan(\theta)=\frac{sin(\theta)}{cos(\theta)}\)

we have

\(sin(\theta)=-\frac{\sqrt{2}}{2}\)

\(cos(\theta)=\frac{\sqrt{2}}{2}\)

substitute

\(tan(\theta)=\frac{-\frac{\sqrt{2}}{2}}{\frac{\sqrt{2}}{2}}\)

\(tan(\theta)=-1\)