Conic Sections Question 77

Question: A tangent to the parabola $ y^{2}=8x $ makes an angle of $ 45^{o} $ with the straight line $ y=3x+5 $ , then the equation of tangent is

Options:

A) $ 2x+y-1=0 $

B) $ x+2y-1=0 $

C) $ 2x+y+1=0 $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

$ m_1=\tan 45{}^\circ =1, $

$ m_2=3 $

Slope of tangent $ =\frac{3\pm 1}{1\mp 3}=-2 $ or $ \frac{1}{2} $

Tangent is $ y=-2x+\frac{2}{-2} $ or $ 2x+y+1=0 $ .