Question

cos5° + cos 10° + cos 15 +_ + cos170° + cos 175° is equal to
1
Zero
-1
2

Answer 1

Answer:

Zero

Step-by-step explanation:

cos 5° + cos 175° = cos 5° + (-cos 5°) = 0

cos 10° + cos 170° = 0

_

cos 90° = 0

Adding all these, we get cos 5° + cos 10° + cos 15° +_+ cos 170° + cos 175° = 0

Answer 2

To find,

cos (5) + cos (10) + cos (15) + cos (20) +___+ cos (170) + cos (175)

Solution,

The following mathematical procedure can be used to solve this mathematical issue.

The method of finding the answer to the given trigonometric equation is as follows.

Now,

⇒ cos (5) + cos (10) + cos (15) + cos (20)___cos (170) + cos (175)

⇒ (cos (5) + cos (175)) + (cos (10) + cos (170)) + __

⇒ (cos (5) + cos (180-5)) + (cos (10) + cos (180-10))+__

⇒ (cos (5) - cos (5) ) + (cos (10) - cos (10)) + __

⇒ 0  

Note:

All the terms of the trigonometric equation will come together to become zero, but cos(90) will be left out. But we know that the value of cos(90) is zero. Thus, the sum will be zero.

Thus,

cos (5) + cos (10) + cos (15) +___ + cos (170) + cos (175) = 0  (Option B)