If you’d like to learn how to confidently find out the size of a wide variety of angles, in different shapes, simply continue reading to discover how to find out the size of most common angles. As an example, you’ll be able to figure out how to find out the value of an angle in a right angled triangle.

How to find the measure of the indicated angle:

1. How to find out the size of an angle in a right angled triangle

To start off with, it’s a great idea to learn how to figure out the easiest angle in geometry, a right angled triangle. To be able to accurately work out a mystery angle in a right angle triangle, you need to know the length of two of your triangle’s three sides.

The three sides of a triangle are named the adjacent angle, which is located adjacent to the angle, the opposite angle and the hypotenuse. It doesn’t matter which two sides you have the measurements of as long as you know the length of two of the three sides which make up your right angled triangle.

The next step which you have to take the figure out your angle is to decide whether to use sine, cosine or tangent. Use sine or sin if you know the lengths of your opposite side and your hypotenuse side. Use cosine if you have the measurements of your adjacent side and your hypotenuse side and if you have opposite side and your adjacent side you’ll need to use tangent.

Once you’ve figured out to use sine, cosine or tangent you’ll ned to use the corresponding formula. As an example if you need to use the sine equation, use the equation Sin (x) = opposite length multiplied by hypotenuse angle = your answer.

A faster way to find out the angle inside a right angled triangle:

If you have a scientific calculator you can save yourself time by using your calculator to perform your equation as scientific calculators have cos, tan and sin buttons.

Tips on how to find angles in a triangle:

If you already know two angles within a triangle, you should be able to figure out the value of the remaining angle without using an algebraic formula. Even if you only know the value of one angle within a triangle, you may be able to figure out the value of the remaining angle, by using the rules below.

1. All the angles within a triangle always add up to 180 degrees.

So if you know two angles within a triangle, simply add both the angles which you have together and subtract them from 180 degrees, to find out the size of your remaining angle.

2. Opposite angles always equal 360 degrees.

If you know the opposite angle within a triangle, you also know how large your mysterious angle is.

Hopefully you now have a few ideas of how you can find out the size of an unknown, mysterious angle in a regular triangle.