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The angle between the tangents to the ci...

The angle between the tangents to the circle with centre (4,5) drawn from P(-2,-3) is `120^(@)` then length of the tagent to the circle from P is

A

a) `5`

B

b) `12`

C

c) `3sqrt(2)`

D

d) `12sqrt(3)`

Text Solution

AI Generated Solution

The correct Answer is:
To find the length of the tangent from point P(-2, -3) to the circle with center (4, 5) and given that the angle between the tangents is 120 degrees, we can follow these steps: ### Step-by-Step Solution: 1. **Identify the Given Information:** - Center of the circle \( O(4, 5) \) - Point from which tangents are drawn \( P(-2, -3) \) - Angle between the tangents \( \angle APB = 120^\circ \) 2. **Determine the Angle at Point O:** - Since \( \angle APB = 120^\circ \), the angle \( \angle OPA \) (where O is the center of the circle) is half of this angle: \[ \angle OPA = \frac{180^\circ - 120^\circ}{2} = 30^\circ \] 3. **Calculate the Length of OP:** - The distance \( OP \) can be calculated using the distance formula: \[ OP = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \] - Substituting the coordinates of O and P: \[ OP = \sqrt{(4 - (-2))^2 + (5 - (-3))^2} \] \[ = \sqrt{(4 + 2)^2 + (5 + 3)^2} \] \[ = \sqrt{6^2 + 8^2} = \sqrt{36 + 64} = \sqrt{100} = 10 \] 4. **Use the Cosine of the Angle to Find AP:** - In triangle \( AOP \), we can use the cosine of angle \( OPA \): \[ \cos(30^\circ) = \frac{AP}{OP} \] - We know \( OP = 10 \) and \( \cos(30^\circ) = \frac{\sqrt{3}}{2} \): \[ \frac{\sqrt{3}}{2} = \frac{AP}{10} \] - Solving for \( AP \): \[ AP = 10 \cdot \frac{\sqrt{3}}{2} = 5\sqrt{3} \] 5. **Conclusion:** - The length of the tangent from point P to the circle is \( AP = 5\sqrt{3} \). ### Final Answer: The length of the tangent to the circle from point P is \( 5\sqrt{3} \).
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