Q&A for How to Use a Protractor

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When do I use the outer scale of the protractor?

Community Answer

The inner scale is for angles that open to the right and the outer scale of the protractor is used to measure angles that open to the left .

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Question

How can I tell whether I need to use a larger or smaller protractor?

Community Answer

The angle on a protractor will always be the same.You may find it easier to have a small protractor when only drawing a small line from the angle you are measuring.

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Question

Why does the protractor have readings on both sides?

Community Answer

So you can read angles form different directions. It's kind of like opposite/mirror images.

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How do I find if the angle is negative or positive?

Donagan

Top Answerer

All angles -- as typically expressed in the context of geometry -- are positive. Any angle you measure with a protractor may be thought of as positive.

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Question

Why is it important to use a protractor?

Community Answer

If you want to precisely find the degrees in an angle, the protractor is probably the best tool.

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Question

Is an obtuse or acute angle better?

Community Answer

There's no better angle, they are simply measurements.

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Question

Does it matter what company the protractor is made by?

Christopher

Top Answerer

No need to worry what company the protract is made by. They all give you accurate measurements of angles, regardless of the company.

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Question

Should I start measuring from the left or from the right?

Donagan

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You can measure from either end.

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Question

Is a right angle 90 degrees?

Christopher

Top Answerer

Yes. A right angle is one that measures 90 degrees. That is common knowledge for any student of math to memorize.

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Question

How do I decide which scale to use when I use a protractor to draw or measure an angle?

Donagan

Top Answerer

The scales are identical. One increases from the left side; the other increases from the right side.

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Question

How do I measure an angle from the upper side?

Donagan

Top Answerer

A protractor has two scales. They are identical but run opposite to each other. Use the scale that starts at zero at the end you want to work from.

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Question

How do I know whether I used the correct scale or not? How would I know when to use the inner scale and when to use the outer scale?

Community Answer

The inner scale is for angles that open to the right and the outer scale of the protractor is used to measure angles that open to the left. Usually the outer scale is mostly used for triangles.

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Question

Which side do I use for a protractor?

Community Answer

You may use any side.

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Question

Do I use a protractor from the right or left side?

Donagan

Top Answerer

A protractor is designed so that you can measure from either side.

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Question

Why do we need to follow the rules when using a protractor?

Community Answer

Using the protactor the right way helps us receive an accurate degree of its measure.

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Question

Which direction does the inner scale of a protractor face? Is it clockwise or counterclockwise?

Community Answer

The inner scale increases clockwise.

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Question

How do I know which scale to use?

Donagan

Top Answerer

The scales are the same "size." One starts at zero at the left end of the arc. The other starts at the right end. This just allows you to measure easily from either end.

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Question

How do I know what kind of protractor to use?

Community Answer

It doesn't matter what kind you use. They all have correct angles and correct measurements.

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Question

What would the reading be if I have a 90 degree specification with +/- 1/4 of a degree?

Donagan

Top Answerer

The reading could range from 89 3/4° to 90 1/4°.

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Question

How do I plot 31 degrees 20 seconds?

Donagan

Top Answerer

31° 20 sec is approximately equal to 31.005°.

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Question

How do you know when to use the top or bottom numbers?

Donagan

Top Answerer

That depends on which side you want to measure from.

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Question

How do I place the protractor on the base line if my protractor has a hole in it?

Community Answer

The hole is for the vertex, it's meant to be there. Place it as outlined in the article steps above.

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Question

Which scale do I use for an obtuse angle?

Donagan

Top Answerer

Either scale will work. They both contain 180°.

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Question

Why do I have to turn a protractor upside down to measure?

Community Answer

You don't really use a protractor upside down when you measure. You turn it to the side. You turn the protractor to the side so that you can make a straight line, and to find which angle you need.

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Question

How do I measure an object that is a reflex angle using a protractor?

Community Answer

If you have a 180 degree protractor, then measure the angle on one side and write the degree down. Then measure from the other side and write that down. Make sure that both degrees are on the same scale by checking the number on the inside or outside (doesn't matter as long as the numbers didn't come from different places), then add them up. What you get should be a reflex angle.

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Question

What is the point of using a protractor even though your never going to use it in everyday life?

Donagan

Top Answerer

The point is to measure angles, perhaps in drawings or diagrams.

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Question

Are square angles called right angles?

Donagan

Top Answerer

The commonly used term is "right angle," which is a 90° angle.

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Question

How can I decide whether to use the left or the right side of a protractor to measure an angle?

Donagan

Top Answerer

Use the side that seems most convenient or useful to you. You'll get the same measurement either way.

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Question

How do you find the measure of an obtuse angle?

Donagan

Top Answerer

A protractor measures angles up to 180°. Measure an obtuse angle the same way you measure an acute angle.

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