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 - ...

In this video I will show you how to verify the cofunction identity using the difference formula for cosine. I make short, to ...

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 ...

Use this formula when given the sizes of two sides and its included angle.