Published by:
CGP EDU Academic Team
Published on: August 13, 2026
Three points A, B, C are taken, on an ellipse, with eccentric angles θ, θ + α and θ + 2 α . Find α (in degrees) for which area of Δ ABC is max.
Text Solution
Verified by ExpertsThe correct answer is:
0120
Ans. 0120
Sol. Area of Δ ABC with vertices
(a cos θ , b sin θ ) (a cos ( θ + α ), b sin ( θ + α ))
and (a cos ( θ + 2 α ), b sin ( θ + 2 α ))
=

=
ab 
=
ab
sin 

= 2ab sin 2 

= 2ab sin 2
sin α
Δ = ab sin α (1 – cos α ) =
[2 sin α – sin 2 α ]
for maximum sin 2 α must be negative and sin α is positive on solving if we get α = 120°
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