The Cosine Rule. How To Work Out The Missing Side Length In A Non Right Angled Triangle.
This video will teach you the cosine rule, so you can calculate the missing side in a non right angled triangle when you are given an angle between two sides, and you need the side opposite the angle. The formula for the cosine rule is a^2 = b^2 + c^2 – 2bcCosA. The small letters are the side lengths and the capital letters are the angles. Since you are finding a side - call this side small a, so the angle opposite this side is capital A . The two other sides of the triangle are b and c – you can label these any order. All you need to do now is substitute these numbers into the cosine rule formula.
This video will teach you the cosine rule, so you can calculate the missing side in a non right angled triangle when you are given an angle between two sides, and you need the side opposite the angle. The formula for the cosine rule is a^2 = b^2 + c^2 – 2bcCosA. The small letters are the side lengths and the capital letters are the angles. Since you are finding a side - call this side small a, so the angle opposite this side is capital A . The two other sides of the triangle are b and c – you can label these any order. All you need to do now is substitute these numbers into the cosine rule formula.