Shortcut Trick
If tan2 θ + cot2 θ = 2, it satisfies the condition x + 1/x = 2, which means tan θ = 1.
For tan θ = 1, the value of θ = 45°.
Substitute θ = 45° in the expression 2sec θ cosec θ.
⇒ 2 × sec 45° × cosec 45° = 2 × √2 × √2 = 2 × 2 = 4.
∴ The correct answer is 4.
Alternate Method
Given: tan2 θ + cot2 θ = 2
Formula Used: sec θ = 1/cos θ and cosec θ = 1/sin θ
⇒ tan2 θ + 1/tan2 θ = 2
⇒ tan4 θ − 2tan2 θ + 1 = 0
⇒ (tan2 θ − 1)2 = 0
⇒ tan2 θ = 1 → tan θ = 1
⇒ θ = 45°
⇒ Value = 2 × sec 45° × cosec 45°
⇒ Value = 2 × (√2) × (√2)
⇒ Value = 2 × 2 = 4
∴ The correct answer is 4.
Additional Information
Reciprocal Identities
Standard relations like tan θ × cot θ = 1, sin θ × cosec θ = 1, and cos θ × sec θ = 1 are fundamental in solving trigonometric equations.
Arithmetic Mean - Geometric Mean (AM-GM) Inequality
For positive values, x + 1/x ≥ 2. The equality x + 1/x = 2 holds true only when x = 1.
Double Angle Relation
The expression 2sec θ cosec θ can be simplified as 2 / (sin θ cos θ) = 4 / (2 sin θ cos θ) = 4 / sin 2θ.