NCERT Class 11-Math's: Exemplar Chapter 3 Trigonometric Functions Part 10
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Question 6:
Prove that
Answer:
To prove:
As equation on RHS is a simplified expression, so we must opt Left side equation and simplify it further so that we can get
LHS = RHS.
And thus we will be able to prove it.
By seeing the expression we can think that the problem can be solved using transformation formula:
By transformation formula, we have:
But as LHS expression does not contain ‘2’ in its term. So we multiply and divide the expression by 2.
Applying transformation formula, we have –
Again, applying the transformation formula:
Hence:
Question 7:
Answer:
Given,
Squaring and adding equation 1 and 2, we get –
Using: , we get –
Question 8:
Find the value of tan ’.
Answer:
Question 9:
Answer:
As we know that-
From T-ratios of multiple angle, we know that
Hence: