Explanation

Identity: 1 + tan²θ = sec²θ

Last verified on 04-05-2026

Explanation

sin²θ + cos²θ = 1  

(3/5)² + cos²θ = 1  

9/25 + cos²θ = 1  

cos²θ = 1 - 9/25  

cos²θ = 16/25  

cosθ = ±4/5  

If θ is acute, cosθ = 4/5

Last verified on 04-05-2026

Explanation

Right triangle: a² + b² = c²  

5² + b² = 13²  

25 + b² = 169  

b² = 169 - 25  

b² = 144  

b = 12  

Last verified on 04-05-2026

Explanation

Third side rule: difference < x < sum  

10 - 7 < x < 10 + 7  

3 < x < 17

16 → 3 < 16 < 17, possible

Last verified on 04-05-2026

Explanation

5/[x(x + 2)] = A/x + B/(x + 2)  

Multiply both sides by x(x + 2)  

5 = A(x + 2) + Bx  

Put x = 0  

5 = A(0 + 2) + B×0  

5 = 2A  

A = 5/2  

Put x = -2  

5 = A(-2 + 2) + B(-2)  

5 = -2B  

B = -5/2  

So 5/[x(x + 2)] = 5/(2x) - 5/[2(x + 2)]

Last verified on 04-05-2026