Which device operates at physical layer

What is the value of 1/(1+tan ²θ ) + 1 / (1+cot ² θ ) = ?

If tan θ = 8/3 , then the value of (3Sinθ+2 Cosθ )/(3 Sinθ-2Cosθ) is

The Value of (sin38˚)/(cos52˚)+ (cos12˚)/(sin78˚)- 4cos²60˚ is

If 1 + sin 2θ = p² and sin³ θ + cos³ θ = q then Which of the following is true ? 

The Value of (sin38˚)/(cos52˚) + (cos12˚)/(sin78˚) - 4cos²60˚ is

If 4sin² θ = 3(1+ cos θ), 0° < θ < 90°, then what is the value of (2tan θ + 4sinθ - secθ)?

If P, Q, R, S are the vertex of a cyclic quadrilateral. Find the value of

`1/sec p` +`1/sec q` +`1/sec r` +`1/sec s`

if a sin 45 ˚ = b cosec 60 ˚ then find the value of a⁴/b⁴