AP EAMCET202120 Aug 2021Evening ShiftMathematicsStraight LinesActual
Find the equation of a line which passes through 2 cos 3 θ , 2 sin 3 θ and is perpendicular to the line x cos θ - y sin θ = 2 cos 2 θ .
Options
- Ax sec θ + y cosec θ = 2
- Bx cosec θ + y sec θ = 2
- Cx sin θ + y cos θ = 2
- Dx cos θ + y sin θ = 2
Correct answer
A. x sec θ + y cosec θ = 2
Step-by-step solution
Given line is x cos θ - y sin θ = 2 cos 2 θ   . . . . 1 ∴   Slope of line 1 is cos θ sin θ Slope of line perpendicular to line 1 is - sin θ cos θ [ ∵ If m 1 & m 2   are slope of perpendicular lines then m 1 . m 2 = - 1 ] Equation of line passing through 2 cos 3 θ , 2 sin 3 θ   & perpendicular to line 1 is y - 2 sin 3 θ = - sin θ cos θ x - 2 cos 3 θ ⇒   y cos θ - 2 sin 3 θ . cos θ = - x sin _