Intermediate Geometry : Lines

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #12 : How To Find Out If Lines Are Parallel

The slopes of two lines on the coordinate plane are 0.333 and .

True or false: the lines are parallel.

Possible Answers:

True

False

Correct answer:

False

Explanation:

Two lines are parallel if and only if they have the same slope. The slope of one of the lines is 0.333. The other line has slope , which is equal to ; this is not equal to 0.333. The two lines are not parallel. 

Example Question #191 : Lines

One line on the coordinate plane has its intercepts at  and . A second line has its intercepts at  and . Are the lines parallel, perpendicular, or neither?

Possible Answers:

Perpendicular

Parallel

Neither

Correct answer:

Perpendicular

Explanation:

To answer this question, we must determine the slopes of both lines. If a line has as its intercepts  and , its slope is

The first line has as its slope 

The second line has as its slope

Two lines are parallel if and only if their slopes are equal; this is not the case. 

They are perpendicular if and only if the product of their slopes is . The product of the slopes of the given lines is

,

so they are perpendicular.

Example Question #13 : How To Find Out If Lines Are Parallel

The slopes of two lines on the coordinate plane are 0.75 and .

True or false: The lines are parallel.

Possible Answers:

True

False

Correct answer:

True

Explanation:

Two lines are parallel if and only if they have the same slope. The slope of one of the lines is . The slope of the other is , so the lines have the same slope. The lines are parallel.

Example Question #192 : Lines

A line which includes the point  is parallel to the line with equation  

Which of these points is on that line?

Possible Answers:

Correct answer:

Explanation:

Write the given equation in slope-intercept form:

The given line has slope , so this is the slope of any line parallel to that line.

We can use the slope formula  , testing each of our choices.

 , which is undefined

 

The only point whose inclusion yields a line with slope  is .

Example Question #1 : How To Find The Slope Of Parallel Lines

Transverselinestilted

If the slope of line AB is 3x, and Angle 1 and Angle 8 are congruent, what is the slope of line CD, and why?

Possible Answers:

(1/3)x, because of the Vertical Angle Theorem

3x, because of the Vertical Angle Theorem

3x, because of the Corresponding Angle Theorem

3x, because of the Alternate Exterior Angle Theorem

(1/3)x, because of the Alternate Exterior Angle Theorem

Correct answer:

3x, because of the Vertical Angle Theorem

Explanation:

Angles 1 and 8 are a vertical pair. If these angles are congruent, it means that lines AB and CD are parallel based on the Vertical Angle Theorem. Parallel lines have the same slope, so the slope of CD is 3x.  

Example Question #1 : How To Find The Slope Of Parallel Lines

Transverselinestilted

The slope of line CD is 4x, and Angle 1 and Angle 5 are congruent. What is the slope of line AB and why?

Possible Answers:

There is not enough information to determine

4x, because of Corresponding Angles Theorem

4x, because of the Vertical Angle Theorem

4x, because of Alternate Interior Angles Theorem

(1/4)x, because of the Corresponding Angle Theorem

Correct answer:

4x, because of Corresponding Angles Theorem

Explanation:

Parallel lines have the same slope. If Angles 1 and 5 are congruent, then lines AB and CD have the same slope (4x) based on the Congruent Angles Theorem. 

Example Question #2 : How To Find The Slope Of Parallel Lines

Any line that is parallel to  must have a slope of what?

Possible Answers:

Correct answer:

Explanation:

Two lines are parallel if and only if they have the same slope. To find the slope, we must put the equation into slope-intercept form,  , where  equals the slope of the line. First, we must subtract  from each side of the equation, giving us . Next, we divide both sides by , giving us . We can now see that the slope is .

Example Question #1481 : Intermediate Geometry

Suppose the equation of the first line is .  What must be the value of  to make the second equation  parallel to the first line?

Possible Answers:

Correct answer:

Explanation:

Rewrite both equations so that they are in slope-intercept form, .

For the first equation:

The slope of the first line is .  

Rewrite the second equation in slope-intercept form:

The value of  must be equal to three to be parallel. Solve for .

Example Question #1 : How To Find The Slope Of Parallel Lines

If the equation of one line is , what must be the slope of another line so that both lines are parallel to each other?

Possible Answers:

Correct answer:

Explanation:

Rewrite the equation of the first line in slope-intercept form, .

The value of the slope, , can be seen as . For another line to be parallel to this line, their slopes must be the same.

Example Question #2 : How To Find The Slope Of Parallel Lines

Find a line parallel to the line with the equation:

 

Possible Answers:

Correct answer:

Explanation:

For two lines to be parallel, they must have the same slope. For a line in , or slope intercept form,  corresponds to the slope of the line.

For the given line, . A line that is parallel must also then have the same slope. 

Only the following line has the same slope:

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