Q.

In the figure, θ1+θ2=π2 and 3 (BE)=4(AB). If the area of ∆CAB is 23-3 unit2, when θ2θ1 is the largest, then the perimeter (in unit) of ∆CED is equal to ______ .              [2023]


Ans.

(6)

Given, 3(BE)=4(AB)

ar(∆CAB)=23-3

So, 12x2tanθ1=23-3

BE=BD+DE

=x(tanθ1+tanθ2)

BE=AB(tanθ1+cotθ1)

43=tanθ1+cotθ1⇒tanθ1=3,13

θ1=π6,θ2=π3;  θ1=π3,θ2=π6

as θ2θ1 is largest

∴  θ1=π6, θ2=π3

∴ x2=(23-3)×2tanθ1=3(2-3)×2tanπ6

⇒ x2=12-63=(3-3)2⇒x=3-3

Perimeter of ∆CED=CD+DE+CE

=3-3+(3-3)3+(3-3)×2=6 units