Share

# If Sec a = 17/8 Verify that (3 - 4sin^2a)/(4 Cos^2 a - 3) = (3 - Tan^2 A)/(1 - 3 Tan^2 A) - CBSE Class 10 - Mathematics

#### Question

if sec A = 17/8 verify that (3 - 4sin^2A)/(4 cos^2 A - 3) = (3 - tan^2 A)/(1 - 3 tan^2 A)

#### Solution

We know sec A = "ℎ𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒"/"𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 𝑠𝑖𝑑𝑒"

Consider right-angled triangle ABC

Let x be the adjacent side

By applying Pythagoras we get

𝐴𝐶2 = 𝐴𝐵2 + 𝐵𝐶2

(17)2 = 𝑥2 + 64

𝑥2 = 289 − 64

𝑥2 = 225 ⇒ 𝑥 = 15

sin A = (AB)/(BC) = 15/17

cos A = (BC)/(AC) = 8/17

tan A = (AB)/(BC) = 15/8

L.H.S = (3 - 4sin^2A)/(4 cos^2 A - 3) = (3 - 4 xx (15/17)^2)/(4xx (8/17)^2 - 3) = (3 -4 xx 225/289)/(4 xx 64/289 - 3) = (867 - 900)/(256 - 867) = (-33)/(-611) = 33/611

R.H.S = (3 - tan^2A)/(1 - 3tan^2 A) = (3 - (15/8)^2)/(1- 3 xx (15/8)^2) = (3 - (225)/64)/(1- 3 xx (225)/64) = ((-33)/64)/((-611)/64) = (-33)/(-611) = 33/611

∴ LHS = RHS

Is there an error in this question or solution?

#### APPEARS IN

Solution If Sec a = 17/8 Verify that (3 - 4sin^2a)/(4 Cos^2 a - 3) = (3 - Tan^2 A)/(1 - 3 Tan^2 A) Concept: Trigonometric Ratios.
S