Right Triangles

Let’s End Things Right

Congratulations! You have made it to the final lesson page. We will end the geometry lesson with the Pythagorean Theorem and formulas for calculating sine, cosine, and tangent. Do you know what these things have in common? If you guessed right triangles, then you were….right!

Pythagorean Theorem

Easily one of the most simple formulas to memorize is the Pythagorean Theorem. Repeat this line out loud: a squared plus b squared equals c squared. Simple algebra, it is. You will be given 2 constants in order to find the missing variable.

Find the missing variable using the Pythagorean Theorem

Sine, Cosine, and Tangent

Think back to the angles and shapes lessons. Remember that a right angle is 90° and the longest side opposite the right angle is the hypotenuse. Now, let’s go a step further. The Greek letter, θ (pronounced theta), is a stand-in similar to using x in algebra. The side connected to the hypotenuse creating angle θ is called the adjacent side. The side opposite θ is called opposite.

For the exam, you need to know how to find the sine, cosine, and tangent. Below are the formulas. This triangle is referred to as ∠ABC. The three individual angles are ∠A, ∠B, and ∠C. Be mindful that θ can also be where
∠B is. This means if you are asked to find sine, cosine, or tangent of ∠B, the sides of adjacent and opposite are going to switch places.

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