In this video, I will show you how to evaluate an angle in degrees using the sum formula of cosine. We will need to use the formula because we cannot evaluate using the unit circle. We will then ...

The cosine rule is: \(a^2 = b^2 + c^2 - 2bc \cos{A}\) This version is used to calculate lengths. Calculate the length BC. Give the answer to three significant figures. Use the form \(a^2 = b^2 + c^2 - ...