Write all the other trigonometric ratios of ∠A in terms of sec A.
Write all the other trigonometric ratios of ∠A in terms of sec A.

Solution:

In terms of sec A, the cos A function:

sec A = 1/cos A

⇒ cos A = 1/sec A

Now write, sec A function in terms of sec A:

cos2A + sin2A = 1

Rearranging the above given terms

sin2A = 1 – cos2A

sin2A = 1 – (1/sec2A)

sin2A = (sec2A-1)/sec2A

sin A = ± √(sec2A-1)/sec A

In terms of sec A cosec A function:

sin A = 1/cosec A

⇒cosec A = 1/sin A

cosec A = ± sec A/√(sec2A-1)

Now write, in terms of sec A tan A function:

sec2A – tan2A = 1

Rearranging the above given terms

⇒ tan2A = sec2A – 1

tan A = √(sec2A – 1)

In terms of sec A cot A function:

tan A = 1/cot A

⇒ cot A = 1/tan A

cot A = ±1/√(sec2A – 1)