Trigonometry : Angles in Different Quadrants

Study concepts, example questions & explanations for Trigonometry

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Example Questions

Example Question #1 : Angles In Different Quadrants

Determine the quadrant that contains the terminal side of an angle measuring \(\displaystyle \frac{-7\pi }{6}\).

Possible Answers:

\(\displaystyle II\)

\(\displaystyle IV\)

\(\displaystyle I\)

\(\displaystyle III\)

Correct answer:

\(\displaystyle II\)

Explanation:

Each quadrant represents a \(\displaystyle \frac{\pi }{2}\) change in radians. Therefore, an angle of \(\displaystyle \frac{-7\pi }{6}\) radians would pass through quadrants \(\displaystyle IV\)\(\displaystyle III\), and end in quadrant \(\displaystyle II\). The movement of the angle is in the clockwise direction because it is negative.

Example Question #2 : Angles In Different Quadrants

Determine the quadrant that contains the terminal side of an angle \(\displaystyle -380^{\circ}\).

Possible Answers:

\(\displaystyle I\)

\(\displaystyle IV\)

\(\displaystyle II\)

\(\displaystyle III\)

Correct answer:

\(\displaystyle IV\)

Explanation:

Each quadrant represents a \(\displaystyle 90^{\circ}\) change in degrees. Therefore, an angle of \(\displaystyle -380^{\circ}\) radians would pass through quadrants \(\displaystyle IV\)\(\displaystyle III\), \(\displaystyle II\)\(\displaystyle I\) and end in quadrant \(\displaystyle IV\). The movement of the angle is in the clockwise direction because it is negative.

Example Question #1 : Angles In Different Quadrants

What quadrant contains the terminal side of the angle \(\displaystyle 240^{\circ}\) ?

Possible Answers:

\(\displaystyle IV\)

\(\displaystyle I\)

\(\displaystyle II\)

\(\displaystyle III\)

Correct answer:

\(\displaystyle III\)

Explanation:

The coordinate plane is divided into four regions, or quadrants. An angle can be located in the first, second, third and fourth quadrant, depending on which quadrant contains its terminal side. When the angle is between \(\displaystyle 180^{\circ}\) and \(\displaystyle 270^{\circ}\), the angle is a third quadrant angle. Since \(\displaystyle 240^{\circ}\) is between \(\displaystyle 180^{\circ}\) and \(\displaystyle 270^{\circ}\), it is a thrid quadrant angle.

 

Example Question #3 : Angles In Different Quadrants

What quadrant contains the terminal side of the angle \(\displaystyle -\frac{\pi}{5}\) ?

Possible Answers:

\(\displaystyle I\)

\(\displaystyle IV\)

\(\displaystyle III\)

\(\displaystyle II\)

Correct answer:

\(\displaystyle IV\)

Explanation:

First we can convert it to degrees:

 

\(\displaystyle -\frac{\pi}{5}\times \frac{180^{\circ}}{\pi}=-36^{\circ}\)

 

The movement of the angle is clockwise because it is negative. So we should start passing through quadrant \(\displaystyle IV\). Since \(\displaystyle -36^{\circ}\) is between \(\displaystyle 0^{\circ}\) and \(\displaystyle -90^{\circ}\), it ends in the quadrant \(\displaystyle IV\).

Example Question #3 : Angles In Different Quadrants

What quadrant contains the terminal side of the angle \(\displaystyle 420^{\circ}\) ?

Possible Answers:

\(\displaystyle II\)

\(\displaystyle III\)

\(\displaystyle I\)

\(\displaystyle IV\)

Correct answer:

\(\displaystyle I\)

Explanation:

The coordinate plane is divided into four regions, or quadrants. An angle can be located in the first, second, third and fourth quadrant, depending on which quadrant contains its terminal side.

 

When the angle is more than \(\displaystyle 360^{\circ}\)  we can divide the angle by \(\displaystyle 360\) and cut off the whole number part. If we divide \(\displaystyle 420^{\circ}\) by \(\displaystyle 360\), the integer part would be \(\displaystyle 1\) and the remaining is \(\displaystyle 60^{\circ}\). Now we should find the quadrant for this angle.

 

When the angle is between \(\displaystyle 0^{\circ}\) and \(\displaystyle 90^{\circ}\), the angle is a first quadrant angle. Since \(\displaystyle 60^{\circ}\) is between \(\displaystyle 0^{\circ}\) and \(\displaystyle 90^{\circ}\), it is a first quadrant angle.

 

Example Question #4 : Angles In Different Quadrants

What quadrant contains the terminal side of the angle \(\displaystyle 820^{\circ}\) ?

Possible Answers:

\(\displaystyle III\)

\(\displaystyle II\)

\(\displaystyle I\)

\(\displaystyle IV\)

Correct answer:

\(\displaystyle II\)

Explanation:

The coordinate plane is divided into four regions, or quadrants. An angle can be located in the first, second, third and fourth quadrant, depending on which quadrant contains its terminal side.

 

When the angle is more than \(\displaystyle 360^{\circ}\) we can divide the angle by \(\displaystyle 360\) and cut off the whole number part. If we divide \(\displaystyle 820^{\circ}\) by \(\displaystyle 360\), the integer part would be \(\displaystyle 2\) and the remaining is \(\displaystyle 100^{\circ}\). Now we should find the quadrant for this angle.

 

When the angle is between \(\displaystyle 90^{\circ}\) and \(\displaystyle 180^{\circ}\), the angle is a second quadrant angle. Since \(\displaystyle 100^{\circ}\) is between \(\displaystyle 90^{\circ}\) and \(\displaystyle 180^{\circ}\), it is a second quadrant angle.

 

 

 

 

Example Question #1 : Angles In Different Quadrants

What quadrant contains the terminal side of the angle \(\displaystyle \frac{10\pi}{3}\) ?

Possible Answers:

\(\displaystyle II\)

\(\displaystyle I\)

\(\displaystyle IV\)

\(\displaystyle III\)

Correct answer:

\(\displaystyle III\)

Explanation:

First we can convert it to degrees:

 

\(\displaystyle \frac{10\pi}{3}\times \frac{180^{\circ}}{\pi}=600^{\circ}\)

 

When the angle is more than \(\displaystyle 360^{\circ}\) we can divide the angle by \(\displaystyle 360\) and cut off the whole number part. If we divide \(\displaystyle 600^{\circ}\) by \(\displaystyle 360\), the integer part would be \(\displaystyle 1\) and the remaining is \(\displaystyle 240^{\circ}\). Now we should find the quadrant for this angle.

 

When the angle is between \(\displaystyle 180^{\circ}\) and \(\displaystyle 270^{\circ}\), the angle is a third quadrant angle. Since \(\displaystyle 240^{\circ}\) is between \(\displaystyle 180^{\circ}\) and \(\displaystyle 270^{\circ}\), it is a third quadrant angle.

 

Example Question #3 : Angles In Different Quadrants

What quadrant contains the terminal side of the angle \(\displaystyle \frac{3\pi}{4}\) ?

Possible Answers:

\(\displaystyle II\)

\(\displaystyle I\)

\(\displaystyle III\)

\(\displaystyle IV\)

Correct answer:

\(\displaystyle II\)

Explanation:

First we can write:

 

\(\displaystyle \frac{3\pi}{4}\times \frac{180^{\circ}}{\pi}=135^{\circ}\)

 

The coordinate plane is divided into four regions, or quadrants. An angle can be located in the first, second, third and fourth quadrant, depending on which quadrant contains its terminal side. When the angle is between \(\displaystyle 90^{\circ}\) and \(\displaystyle 180^{\circ}\), the angle is a second quadrant angle. Since \(\displaystyle 135^{\circ}\) is between \(\displaystyle 90^{\circ}\) and \(\displaystyle 180^{\circ}\), it is a second quadrant angle.

Example Question #64 : Angles

In what quadrant does \(\displaystyle -120^\circ\) lie? 

Possible Answers:

4th 

3rd 

2nd 

1st 

What are quadrants? 

Correct answer:

3rd 

Explanation:

When we think of angles, we go clockwise from the positive x axis.

Thus, for negative angles, we go counterclockwise. Since each quadrant is defined by 90˚, we end up in the 3rd quadrant. 

Example Question #1 : Angles In Different Quadrants

Which of the following answers best represent \(\displaystyle tan(315)\)?

Possible Answers:

\(\displaystyle \frac{\sqrt2}{2}\)

\(\displaystyle 1\)

\(\displaystyle \frac{\pi}{4}\)

\(\displaystyle -1\)

\(\displaystyle \sqrt2\)

Correct answer:

\(\displaystyle -1\)

Explanation:

The angle 315 degrees is located in the fourth quadrant.  The correct coordinate designating this angle is \(\displaystyle (1,-1)\).

The tangent of an angle is \(\displaystyle \frac{y}{x}\).

Therefore, 

\(\displaystyle tan(315)= \frac{y}{x}= \frac{-1}{1}=-1\)

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