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Angle between the tangents drawn to para...

Angle between the tangents drawn to parabola `y^(2)+4a^(2)-4ax=0`, from origin is :

A

`30^(@)`

B

`tan^(-1)(2)`

C

`90^(@)`

D

`tan^(-1)((1)/(2))`

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To find the angle between the tangents drawn to the parabola \( y^2 + 4a^2 - 4ax = 0 \) from the origin, we can follow these steps: ### Step 1: Rewrite the equation of the parabola The given equation of the parabola is: \[ y^2 + 4a^2 - 4ax = 0 \] We can rearrange this to: \[ y^2 = 4ax - 4a^2 \] ### Step 2: Substitute the tangent line equation The equation of a line passing through the origin can be expressed as: \[ y = mx \] where \( m \) is the slope of the line. We will substitute \( y = mx \) into the parabola's equation. ### Step 3: Substitute and simplify Substituting \( y = mx \) into the parabola's equation gives: \[ (mx)^2 + 4a^2 - 4ax = 0 \] This simplifies to: \[ m^2x^2 - 4ax + 4a^2 = 0 \] ### Step 4: Apply the condition for tangency For the line to be tangent to the parabola, the discriminant of this quadratic equation must be zero. The discriminant \( D \) is given by: \[ D = b^2 - 4ac \] Here, \( a = m^2 \), \( b = -4a \), and \( c = 4a^2 \). Therefore, we have: \[ D = (-4a)^2 - 4(m^2)(4a^2) = 16a^2 - 16a^2m^2 \] Setting the discriminant to zero for tangency: \[ 16a^2(1 - m^2) = 0 \] ### Step 5: Solve for \( m \) Since \( 16a^2 \) cannot be zero (as \( a \) is a constant), we have: \[ 1 - m^2 = 0 \implies m^2 = 1 \implies m = \pm 1 \] ### Step 6: Write the equations of the tangents The slopes of the tangents are \( m = 1 \) and \( m = -1 \). Therefore, the equations of the tangents are: \[ y = x \quad \text{and} \quad y = -x \] ### Step 7: Find the angle between the tangents The angle \( \theta \) between two lines with slopes \( m_1 \) and \( m_2 \) can be calculated using the formula: \[ \tan \theta = \left| \frac{m_1 - m_2}{1 + m_1 m_2} \right| \] Here, \( m_1 = 1 \) and \( m_2 = -1 \): \[ \tan \theta = \left| \frac{1 - (-1)}{1 + (1)(-1)} \right| = \left| \frac{2}{0} \right| \] Since the denominator is zero, this indicates that the angle \( \theta \) is \( 90^\circ \). ### Conclusion The angle between the tangents drawn to the parabola from the origin is: \[ \theta = 90^\circ \]

To find the angle between the tangents drawn to the parabola \( y^2 + 4a^2 - 4ax = 0 \) from the origin, we can follow these steps: ### Step 1: Rewrite the equation of the parabola The given equation of the parabola is: \[ y^2 + 4a^2 - 4ax = 0 \] We can rearrange this to: ...
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