1)Sketch \(45°\) in standard position. State the quadrant and reference angle.
The initial side lies on the positive \(x\)-axis. Rotate counterclockwise \(45°\).
The terminal side is between \(0°\) and \(90°\), so it is in Quadrant I.
\(\color{red}{\text{Quadrant I; reference angle }45°}\)
2)Sketch \(120°\) in standard position. State the quadrant and reference angle.
Since \(90°<120°<180°\), the terminal side is in Quadrant II.
The reference angle is \(180°-120°=60°\).
\(\color{red}{\text{Quadrant II; reference angle }60°}\)
3)Sketch \(225°\) in standard position. State the quadrant and reference angle.
Since \(180°<225°<270°\), the terminal side is in Quadrant III.
The reference angle is \(225°-180°=45°\).
\(\color{red}{\text{Quadrant III; reference angle }45°}\)
4)Sketch \(315°\) in standard position. State the quadrant and reference angle.
Since \(270°<315°<360°\), the terminal side is in Quadrant IV.
The reference angle is \(360°-315°=45°\).
\(\color{red}{\text{Quadrant IV; reference angle }45°}\)
5)Sketch \(-60°\) in standard position. State the quadrant and reference angle.
A negative angle rotates clockwise from the positive \(x\)-axis.
Clockwise \(60°\) lands in Quadrant IV.
\(\color{red}{\text{Quadrant IV; reference angle }60°}\)
6)Sketch \(450°\) in standard position. State where the terminal side lies.
Subtract one full turn: \(450°-360°=90°\).
An angle of \(90°\) lies on the positive \(y\)-axis.
\(\color{red}{\text{Terminal side on the positive }y\text{-axis}}\)
7)Sketch \(\frac{7π}{6}\) in standard position. State the quadrant and reference angle.
\(\frac{7π}{6}=\pi+\frac{π}{6}\), so the terminal side is past \(π\).
That places the angle in Quadrant III.
\(\color{red}{\text{Quadrant III; reference angle }\frac{π}{6}}\)
8)Sketch \(-\frac{3π}{4}\) in standard position. State the quadrant and reference angle.
Add \(2π\): \(-\frac{3π}{4}+2π=\frac{5π}{4}\).
\(\frac{5π}{4}\) lies in Quadrant III.
\(\color{red}{\text{Quadrant III; reference angle }\frac{π}{4}}\)
9)Sketch \(\frac{5π}{2}\) in standard position. State where the terminal side lies.
Subtract \(2π=\frac{4π}{2}\): \(\frac{5π}{2}-\frac{4π}{2}=\frac{π}{2}\).
\(\frac{π}{2}\) lies on the positive \(y\)-axis.
\(\color{red}{\text{Terminal side on the positive }y\text{-axis}}\)
10)Sketch \(\frac{11π}{3}\) in standard position. State the quadrant and reference angle.
Subtract \(2π=\frac{6π}{3}\): \(\frac{11π}{3}-\frac{6π}{3}=\frac{5π}{3}\).
\(\frac{5π}{3}\) lies in Quadrant IV.
\(\color{red}{\text{Quadrant IV; reference angle }\frac{π}{3}}\)
11)Sketch \(-\frac{11π}{6}\) in standard position. State the quadrant and reference angle.
Add \(2π=\frac{12π}{6}\): \(-\frac{11π}{6}+\frac{12π}{6}=\frac{π}{6}\).
\(\frac{π}{6}\) lies in Quadrant I.
\(\color{red}{\text{Quadrant I; reference angle }\frac{π}{6}}\)
12)Sketch \(\frac{13π}{4}\) in standard position. State the quadrant and reference angle.
Subtract \(2π=\frac{8π}{4}\): \(\frac{13π}{4}-\frac{8π}{4}=\frac{5π}{4}\).
\(\frac{5π}{4}\) lies in Quadrant III.
\(\color{red}{\text{Quadrant III; reference angle }\frac{π}{4}}\)
13)Sketch \(720°\) in standard position. State where the terminal side lies.
\(720°\) is two full counterclockwise rotations.
After full rotations, the terminal side returns to the positive \(x\)-axis.
\(\color{red}{\text{Terminal side on the positive }x\text{-axis}}\)
14)Sketch \(-210°\) in standard position. State the quadrant and reference angle.
Add \(360°\): \(-210°+360°=150°\).
\(150°\) lies in Quadrant II, and \(180°-150°=30°\).
\(\color{red}{\text{Quadrant II; reference angle }30°}\)
15)Sketch \(1000°\) in standard position. State the quadrant and reference angle.
Subtract \(720°\): \(1000°-720°=280°\).
\(280°\) lies in Quadrant IV, and \(360°-280°=80°\).
\(\color{red}{\text{Quadrant IV; reference angle }80°}\)
16)Sketch \(-\frac{19π}{6}\) in standard position. State the quadrant and reference angle.
Add \(4π=\frac{24π}{6}\): \(-\frac{19π}{6}+\frac{24π}{6}=\frac{5π}{6}\).
\(\frac{5π}{6}\) lies in Quadrant II.
\(\color{red}{\text{Quadrant II; reference angle }\frac{π}{6}}\)
17)Sketch \(\frac{17π}{3}\) in standard position. State the quadrant and reference angle.
Subtract \(4π=\frac{12π}{3}\): \(\frac{17π}{3}-\frac{12π}{3}=\frac{5π}{3}\).
\(\frac{5π}{3}\) lies in Quadrant IV.
\(\color{red}{\text{Quadrant IV; reference angle }\frac{π}{3}}\)
18)Sketch \(-765°\) in standard position. State the quadrant and reference angle.
Add \(1080°\): \(-765°+1080°=315°\).
\(315°\) lies in Quadrant IV, and \(360°-315°=45°\).
\(\color{red}{\text{Quadrant IV; reference angle }45°}\)
19)Sketch \(\frac{31π}{6}\) in standard position. State the quadrant and reference angle.
Subtract \(4π=\frac{24π}{6}\): \(\frac{31π}{6}-\frac{24π}{6}=\frac{7π}{6}\).
\(\frac{7π}{6}\) lies in Quadrant III.
\(\color{red}{\text{Quadrant III; reference angle }\frac{π}{6}}\)
20)Sketch \(-\frac{25π}{4}\) in standard position. State the quadrant and reference angle.
Add \(8π=\frac{32π}{4}\): \(-\frac{25π}{4}+\frac{32π}{4}=\frac{7π}{4}\).
\(\frac{7π}{4}\) lies in Quadrant IV.
\(\color{red}{\text{Quadrant IV; reference angle }\frac{π}{4}}\)