Q304
The value of expression cos245° + cos2135° + cos2225° + cos2315° is:
A.
2
AnswerB.
C.
D.
1
Answer: Option A
Solution
Answer: Option A
Solution:
cos245° + cos2135° + cos2225° + cos2315°= (cos245° + cos2315°) + (cos2135° + cos2225°) [Here cos2α + cos2β = 1, where α + β = 360°]
= 1 + 1
= 2