Answer and Explanation
Your Answer is
Correct Answer is G
Explanation
∠ECD=∠A+∠CBA, that is, α + β =60, so the cosine value of 60° is the desired value
54. The angle measures of △CDE are shown below. Point B of △ABC lies on CD ,and point C lies on AE. What is the value of cos(α+β) ?
(Note: cos30°=
)
