Answer the following without using trigonometric tables or a calculator.

MATHEMATICS · Multi-part · CBSE · Mathematics · Introduction to Trigonometry · Introduction to Trigonometry

Problem

Answer the following without using trigonometric tables or a calculator. (i) Explain, with the help of a right-angled triangle, whether the value of

\sin\theta

increases or decreases as

\theta

increases from

0^{\circ}

90^{\circ}

. Similarly comment on

\cos\theta

. (ii) Using your explanation in part (i), decide which of the two numbers

\sin 28^{\circ}

and

\sin 34^{\circ}

is larger. Give reason for your answer. (iii) Without actual computation, determine which is larger:

\cos 28^{\circ}

\sin 62^{\circ}

. Give a suitable justification.