I’m pretty certain you’re familiar with a protractor. If not, a protractor is usually provided to measure an angle accurately.

You are watching: How to measure an angle without a protractor

What if there’s no protractor in hand? worry no an ext because you deserve to measure an angle also with no protractor.

Here’s how:

Step 1: acquire a ruler and measure the exact distance the both sides from the origin point of the edge (Should be the similar distance because that both sides). Take it a pen and document to record all the measurements.

Step 2: Label the distance as “D” and mark the 2 points ~ above the angle. It should be a size away from the point of origin. Labeling ~ you measure up it will help you identify each angle suggest easily.

Step 3: Use the leader again to uncover the accurate distance in between the 2 points ~ above the angle and also record the dimensions on the paper.

Step 4: You will need to label the measured distance in between the 2 points together “E.” This is to identify it native the vault measurement you did. Failure to record will result in confusion while act measurements and calculations later on.

Step 5: Apply this Sine Formula: Angle measure = 2 x arcsin (0.5 x e/d). Entry the worths you’ve measured previously for “D” and also “E.”

Step 6: Furthermore, this formula is acquired from the yes, really equation because that the provided sine actions of the next of the right triangle. The angle’s sine have to be equal to the measure up of the opposite side of the angle and divided through the measure up of the triangle’s hypotenuse.

Step 7: Solve the angle measure using your graphing calculator. Encode number “2” and also press the multiplication symbol. Then push “arcsin” and the worth that is fifty percent of “D” and also “E.”

Step 8: Double-check the encoded values, then push “Enter” or the “=” authorize to acquire the final answer or solution. Make sure you’ve encoded the best values correctly, or friend will gain the dorn answer.

Step 9: For this formula, friend can likewise use the calculator’s second key to solve it. Simply press “arcsin,” i beg your pardon you have the right to see from the same key as the sin.

Step 10: friend should acquire the final answer properly as quickly as you reach this step. If you have actually a protractor or plans to grab one, later on on, you can verify your answer and check if castle were exact or not.

You can also bisect angle without a protactor

There’s a lot the you can do various other than measuring without a protractor. Talking earlier going ago to basics, girlfriend can also bisect angle without using a protractor. Because that a quick refresher, bisecting an angle means to divide the angle right into two same parts. It is the line that you check out that splits one angle right into two same parts.

Here’s how to bisect the angle without a protractor:

Step 1: Use a compass to and place that on the crest of the angle, which is allude B.

Step 2: You will need to attract an arc from throughout each eight of the angle.

Step 3: Position her compass ~ above the allude where it intersects one arm and also draw one more arc ~ above the inside of the angle.

Step 4: Repeat the same procedure for the various other arm without transforming the compass’ width so the the 2 arms will intersect from every other.Step 5: By utilizing a ruler, attach the vertex to the allude where the arcs intersect, i m sorry is at allude D. The bisector of alphabet is DB.

Step 6: To bisect the angles, use your compass and ruler for accuracy.

Constructing one-of-a-kind Angles without a Protractor

Step 1: You will need to attract a heat segment of points L and M.

Step 2: Draw one arc throughout LM that goes increase over allude L.

Step 3: Move the compass to the direction wherein the allude of the arc intersects allude LM. Make certain you walk not change the width of the compass.

Step 4: Draw another arc that crosses the an initial arc that you drew.

Step 5: Then connect suggest L come the allude where the two arcs meet.

Important things to remember

Ensure that you make dimensions accurately. It’s constantly recommended to conduct measurements at the very least twice to verify that correctness.It won’t hurt to compare your answers as soon as using a protractor. This will aid you practice and also learn better.

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There you have it! It could be easier to measure, bisect, and also construct angles utilizing protractors. However, it’s also an excellent to note that you deserve to actually do it there is no it. Her geometry an abilities will additionally improve once you begin doing it manually. Therefore the next time you don’t have a protractor, you’re an excellent to go!

Can you usage a ruler instead of a protractor?


A protractor
is the usual tool for the job. Once a protractor is no available, however, an plain ruler and a calculator will certainly suffice. Hold one of the present so that it is level through the ground.