2025 · Standard · Set 5 · Part 2·Q25·2 marks

Introduction to Trigonometry

Question

If $sin A = y$ , then express $cos A$ and $tan A$ in terms of y.

Approach

Using $sin^{2} A + cos^{2} A = 1$ , we get $cos A = 1 - y^{2}$ (for acute angle). Then $tan A = \frac{s i n A}{c o s A} = \frac{y}{1 - y ^{2}}$ .

Step-by-step working

1
$cos A = 1 - y^{2}$
1 mark
2
$tan A = \frac{y}{1 - y ^{2}}$
1 mark

Concepts used

trigonometric identitiessincostan

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