if cos2A=sin(A-15), find A
Answers
Answered by
225
cos 2A = sin (A - 15)
cos 2A = cos ( 90 - (A - 15) )
2A = 90 - A + 15
3A = 105
A = 35
cos 2A = cos ( 90 - (A - 15) )
2A = 90 - A + 15
3A = 105
A = 35
Answered by
1
Answer:
The value of A = 35
Step-by-step explanation:
Given
cos 2A = sin(A - 15)
Recall the concept
Complementary angles are angles whose sum is 90degrees
From the trigonometric identities of complement angles we get
sin(90 - ) = cos
Solution
Given, cos 2A = sin(A - 15)
We know
The complementary angle of 2A = 90 - 2A
Hence, we have
cos 2A = sin(90-2A)
substituting in the given equation we get
Sin(90-2A) = sin(A -15)
Comparing we get
90-2A = A -15
3A = 90+15
3A = 105
A = = 35
The value of A = 35
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