Question

What is the length of the tangent to the circle x² + y² = 9 from the point (4, 0).
1. √7 units
2. √6 units
3. √11 units
4. √17 units
5. None of these

Answer 1

Correct Answer - Option 1 : √7 units

Concept:

The length of the tangent from an external point (x₁, y₁) to the circle x² + y² = a² is \(\sqrt {x_1^2 + y_1^2 - {a^2}}\)

Calculation:

Given: Equation of circle x² + y² = 9 and the point (4, 0).

As we know that, the length of the tangent from an external point (x₁, y₁) to the circle x² + y² = a² is \(\sqrt {x_1^2 + y_1^2 - {a^2}}\)

Here, x₁ = 4 , y₁ = 0 and a² = 9.

So, the length of the tangent is √7 units.