Intermediate Geometry : Lines

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #8 : How To Find Out If Lines Are Perpendicular

Are the lines of the equations 

and

parallel, perpendicular, or neither?

Possible Answers:

Perpendicular

Parallel

Neither

Correct answer:

Neither

Explanation:

Write each equation in the slope-intercept form  by solving for ; the -coefficient  is the slope of the line.

Subtract  from both sides:

The line of this equation has slope .

 

Subtract  from both sides:

Multiply both sides by 

The line of this equation has slope .

Two lines are parallel if and only if they have the same slope; this is not the case. They are perpendicular if and only if the product of their slopes is ; this is not the case, since

.

The correct response is that the lines are neither parallel nor perpendicular.

Example Question #9 : How To Find Out If Lines Are Perpendicular

Are the lines of the equations 

and

parallel, perpendicular, or neither? 

Possible Answers:

Parallel 

Perpendicular

Neither

Correct answer:

Neither

Explanation:

Write each equation in the slope-intercept form  by solving for ; the -coefficient  is the slope of the line.

Subtract  from both sides:

Multiply both sides by :

The slope is the -coefficient 

 

Add  to both sides:

Multiply both sides by :

The slope is the -coefficient .

Two lines are parallel if and only if they have the same slope; this is not the case. They are perpendicular if and only if the product of their slopes is ; this is not the case, since . The lines are neither parallel nor perpendicular.

Example Question #1 : How To Find Out If Lines Are Perpendicular

The slopes of two lines on the coordinate plane are  and 4. 

True or false: the lines are perpendicular.

Possible Answers:

True

False

Correct answer:

True

Explanation:

Two lines on the coordinate plane are perpendicular if and only if the product of their slopes is . The product of the slopes of the lines in question is

,

so the lines are indeed perpendicular.

Example Question #11 : How To Find Out If Lines Are Perpendicular

Two lines intersect at the point . One line passes through the point ; the other passes through .

True or false: The lines are perpendicular.

Possible Answers:

True

False

Correct answer:

False

Explanation:

Two lines are perpendicular if and only if the product of their slopes is . The slope of each line can be found from the coordinates of two points using the slope formula

To find the slope of the first line, set :

To find the slope of the second line, set :

The product of the slopes is

As the product is not , the lines are not perpendicular.

Example Question #171 : Lines

The slopes of two lines are 6 and . True or false: the lines are perpendicular. 

Possible Answers:

True

False

Correct answer:

False

Explanation:

Two lines on the coordinate plane are perpendicular if and only if the product of their slopes is . The product of the slopes of the lines in question is

The product is not equal to , so the lines are not perpendicular.

Example Question #1 : Parallel Lines

Transverselines

Which answer contains all the angles (other than itself) that are congruent to Angle 1?

Possible Answers:

Angles 2 and 5

Angles 4 and 5

Angles 8 and 6

Angles 4, 5, and 8

Angles 2 and 4

Correct answer:

Angles 4, 5, and 8

Explanation:

Because of the Corresponding Angles Theorem (Angle 2 and Angle 5), Alternate Exterior Angles (Angle 2 and Angle 8), and Vertical Angles (Angle 2 and Angle 4). 

Example Question #2 : Parallel Lines

Transverselines

Angles 2 and 3 are congruent based on which Theorem?

Possible Answers:

Alternate Exteriors Angles

Consecutie Internior Angles

Vertical Angles

Corresponding Angles

Alternate Interior Angles

Correct answer:

Vertical Angles

Explanation:

Veritcal angles means that the angles share the same vertex. Angles 2 and 3 are a vertical pair of angles, which mean that they are congruent. 

Example Question #3 : Parallel Lines

Transverselines

If angles  2 and 6 are congruent, lines AB and CD are parallel based on which theorem? 

Possible Answers:

Consecutive Interior Angles

Vertical Angles 

Corresponding Angles

Alternate Exterior Angles

Alternate Interior Angles

Correct answer:

Corresponding Angles

Explanation:

Angles 2 and 6 are Corresponding Angles. If each of the set of angles were taken separately, angels 2 and 6 would occupy the same place and are thus corresponding angles. 

Example Question #4 : Parallel Lines

Transverselines

What is the sum of Angle 3 and Angle 5?

Possible Answers:

15 deg

45 deg

90 deg

360 deg

180 deg

Correct answer:

180 deg

Explanation:

Because of the Consecutive Interior Angle theorem, the sum of Angles 3 and 5 would be 180 deg. 

Example Question #5 : Parallel Lines

Transverselines

If lines AB and CD are parallel, angles 1 and 8 are congruent based on which theorem?

Possible Answers:

Alternate Interior Angles

Vertical Angles

Corresponding Angles

Alternate Exterior Angles

Consecutive Interior Angles

Correct answer:

Alternate Exterior Angles

Explanation:

Angles 1 and 8 are on the exterior of the parallel lines and are on opposite sides of the transversal. This means the Theorem is the Alternate Exterior Angle theorem. 

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