Question

15. यदि 9 cos A+40 sin A = 41 हो, तो cos A और cosec A का मान ज्ञात करें।​

Answer 1

Answer:

i) Dividing both sides by 41, (9/41)*cos(A) + (40/41)*sin(A) = 1 

ii) This is of the form, cos(A)*cos(B) + sin(A)*sin(B) = 1, where cos(B) = 9/41 and sin(B) = 40/41 

iii) So, cos(A - B) = 1 

==> A - B = 2nπ 

Hence A = 2nπ + B 

iv) So, cos(A) = cos(2nπ + B) = cos(B) = 9/41 

csc(A) = csc(2nπ + B) = csc(B) = 41/40

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