Book- ML Aggarwal

Board- ICSE

Publication- Avichal

Chapter- Trigonometric Identities

If A is an acute angle and sec A = 17/8, find all other trigonometric ratios of angle A (using trigonometric identities).

This is important ques.. Pls provide solution with figure

ML Aggarwal, ques no 2

Solution:Given that

sec A = 17/8 and A is an acute angle

So, in ∆ ABC we have ∠B = 90

^{o}And,

AC = 17 and AB = 8

By Pythagoras theorem,

BC = √(AC

^{2}– AB^{2})= √(17

^{2}– 8^{2}) = √(289 – 64)= √225= 15

Now,

sin A = BC/AC = 15/17

cos A = 1/sec A = 8/17

tan A = BC/AB = 15/8

cot A = 1/tan A= 8/15

cosec A = 1/sin A = 17/15