In the diagram shown, ABCD is a square and point F lies on BC. △DEC is equilateral and EB=EF. What is the measure of ∠EBC?
Answer:
75∘
- Given, ABCD is a square, △DEC is an equilateral triangle and EB=EF.
⟹∠DCB=90∘ and ∠DCE=60∘
⟹∠ECF=30∘ - Since DC=CE [Sides of an equilateral triangle]
and DC=CB [Sides of a square]
⟹CE=CB
⟹△ECB is an isosceles triangle.
⟹∠EBC=∠BEC [∵
Now, \angle ECB + \angle EBC + \angle BEC = 180^\circ \space\space\space\space\space\space\space\space\space\space\space\space [\text{ Angle Sum Property of a triangle}]
\implies \angle EBC + \angle EBC + 30^\circ = 180^\circ
\implies \angle EBC = \dfrac{ (180 - 30) } { 2 } = 75^\circ - Given, EB = EF
\therefore \angle BFE = \angle EBC = 75^\circ - Hence, the value of \angle EBC is \angle 75^\circ.