In △CDE , DE=15 , CE=7 , and m∠E=38°. What is the length of ⎯⎯⎯⎯⎯⎯
CD?
Enter your answer, rounded to the nearest hundredth.
CD =
C
7
D 15 E = 38°
We can use the Law of Cosines to solve this
CD = √ [ CE^2 + DE^2 - 2(CE * DE)* cos (38°) ]
CD = √ [ 7^2 + 15^2 - 2 (7 * 15)* cos (38°) ]
CD = √ [ 49 + 225 - 210cos(38°) ]
CD = √[274 - 210cos(38°) ]
CD ≈ 10.42
