Question

In △CDE, DE=14, CE=9, and m∠E=71∘. What is the length of CD⎯⎯⎯⎯⎯⎯? Enter your answer, rounded to the nearest hundredth, in the box.

Answer 1

13.96units

Explanation:

To get the length of CD, we will use the cosine rule as shown:

CD² = DE²+CE²-2(DE)(CE)cos m<E

Substitute the given values

CD² = 14²+9²-2(14)(9)cos71

CD² = 196 + 81 - 252cos71

CD² =277 - 252cos71

CD² = 277 - 82.0431

CD² = 194.95682

CD = √194.95682

CD = 13.96 units

Hence the length of CD of 13.96units