Question

If tan 2A = cot (A – 18°), where 2A is an acute angle, find the value of A. NCERT Class X Mathematics - Mathematics Chapter _INTRODUCTION TO TRIGONOMETRY

Answer 1

Cot (90-A)= cot (2a-18)
90-A=2A-18
3A=108
A=36

Answer 2

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Answer:

36°

Step-by-step explanation:

 It is given that tan2A=cot(A−18°)

 ⇒tan2A=cot(90° −(108° −A))

⇒tan2A=tan(108° −A)        

{°•° cot(90° −A)=tan(A)}

 ⇒2A=108° −A

 ⇒3A=108°

 ⇒A=108°/3 =36°

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