Question

Find the value of :cos theta+cos(π+theta)+ cos (2π+theta+........to 20 terms.




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Answer 1

Step-by-step explanation:

Solution,

= cos theta+cos(π+theta)+ cos (2π+theta+........to 20

= cos theta - cos theta + cos theta - cos theta +............ + cos theta - cos theta

= 0 Ans

In the questions, concept

When, cos ( odd number of pie + theta) = - cos theta

And cos ( even number of pie + theta) = cos theta