In the given triangle ABC, BC is produced to D. BF and FCare the bisectors of ZABC and ZACD respectively. IfZBAC = 70° and EF = EC, then the measure of FEC isequal toAF70°suBсD80°55°110°75°
Answers
Answer:
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Answer:
Step-by-step explanation:
Given:The given triangle ABC, BC is produced to D. BF and FC are the bisectors of ABC and ACD respectively. If BAC 70° and EF = EC.
To find: Measure of FEC is equal to
Solution:
Let
\begin{gathered}\angle FBC= \angle ABF= x \\ \\ and \\ \\ \angle ACF= \angle FCD= y \\\end{gathered}
∠FBC=∠ABF=x
and
∠ACF=∠FCD=y
Apply exterior angle property of triangle on ∆ABC
\begin{gathered}70° + 2x = 2y \\ \\ or \\ \\ 35° + x = y \\ \\ y-x=35°...eq1\end{gathered}
70°+2x=2y
or
35°+x=y
y−x=35°...eq1
let us assume
\begin{gathered}\angle BFC= r \\ \\\end{gathered}
∠BFC=r
Apply exterior angle property on ∆ FBC
\begin{gathered}r + x = y \\ \\ or \\ \\ r = y - x \\ \\ r = 35°\:(from\:eq1) \\ \\\end{gathered}
r+x=y
or
r=y−x
r=35°(fromeq1)
now since triangle FEC is isosceles triangle, so angle ECF will also be r.
By angle sum property of triangle we can write
\begin{gathered}\angle FEC + r + r= 180° \\ \\ \angle FEC + 70°= 180° \\ \\ \angle FEC = 180° -70°\\ \\ \angle FEC = 110° \\ \\\end{gathered}
∠FEC+r+r=180°
∠FEC+70°=180°
∠FEC=180°−70°
∠FEC=110°
Hope it helps you.
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