Q50 of 59 Page 178

State whether the statements are true or false.

Equation of the line passing through the point (a cos3θ, a sin3θ) and perpendicular to the line x sec θ + y cosec θ = a is x cos θ – y sin θ = a sin 2θ.

Let the equation of line y = mx + c …(i)

So, slope of the above equation is ‘m’


Given equation of line is x sec θ + y cosec θ = a


y cosecθ = a – x secθ



Since the above equation is in y = mx + b form


So, slope of the equation is



Given that eq. (i) is perpendicular to x sec θ + y cosec θ = a


m × m’ = -1




Putting the value of m in eq. (i), we get




y secθ = x cosecθ + c (secθ)


x cosecθ – y secθ = - c secθ


x cosecθ – y secθ = k …(ii)


[Let k = - c secθ]


If eq. (ii) passes through the point (a cos3θ, a sin3θ)


(a cos3θ) cosecθ – (a sin3θ) secθ = k






a[(cos2θ – sin2θ)(cos2θ + sin2θ)] = xcosθ – ysinθ


[(a4 – b4) = (a2 – b2)(a2 + b2)]


a[(cos2θ – sin2θ)(1)] = xcosθ – ysinθ


[cos2θ + sin2θ = 1]


a[cos 2θ] = xcosθ – ysinθ


[cos2θ – sin2θ = cos 2θ]


xcosθ – ysinθ = a cos 2θ


Hence, the given statement is FALSE


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