Questions: Suppose θ is in the interval 90°<θ<180°. Find the sign of the following.
sin(θ+90°)
Choose whether the sign of sin (θ+90°) is positive or negative.
Negative
Positive
Transcript text: Suppose $\theta$ is in the interval $90^{\circ}<\theta<180^{\circ}$. Find the sign of the following.
\[
\boldsymbol{\operatorname { s i n }}\left(\theta+90^{\circ}\right)
\]
Choose whether the $\operatorname{sign}$ of $\sin \left(\theta+90^{\circ}\right)$ is positive or negative.
Negative
Positive
Solution
Solution Steps
Step 1: Identify the Quadrant
The original angle \(\theta = 135^\circ\) lies in the second quadrant.
After applying the transformation +90, the angle becomes \(\theta = 225^\circ\).
This places the angle in the 3 quadrant.
Step 2: Apply Trigonometric Function Signs
In the 3 quadrant, the sign of the sin function is '-'.
Final Answer:
The sign of the sin function, after applying the transformation +90 to an angle in the second quadrant, is '-'.