frac{4^2 + 6.9^2 - 4.2^2}{2 \times 4 \times 6.9}\) \(\cos{y} = 0.8327898 \dotsc\). Do not round this answer yet. To calculate the angle use the inverse cos button on the calculator (\(\cos^{-1}\)).

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