Question

pls solve this.... This is an urgent question

Answer 1

Hola there,

Let theta be 'A'

Given => tanA = 1/√3

So, we can conclude that,
A = 30°

So, now we have to prove that => 7sin²A + 3cos²A = 4

LHS

=> 7sin²A + 3cos²A

=> 7sin²30° + 3cos²30°

=> 7(1/2)² + 3(√3/2)²

=> 7/4 + 9/4

=> 16/4

=> 4

=> RHS

So, LHS = RHS

Hence Proved

Hope this helps...:)

Answer 2

Given that:

tan ϴ = 1/√3

you might know that tan 30° = 1 /√3

Therefore,

tan ϴ = tan 30°

Therefore, ϴ = 30°


I'll be using LHS to prove this,


7sin²ϴ + 3cos²ϴ

substitute for ϴ in above equation

7sin²30° + 3cos²30°


(as sin 30° = 1/2 and cos 30° = √3/2)


= 7(1/2)² + 3(√3/2)²
= 7/4 + 3(3/4)
= 7/4 +9/4
= 16/4
= 4

aa LHS = RHS

Hence proved.