Find the following?

enter image source here

1 Answer
CW
Jul 31, 2017

#angleACB=100^@#

Explanation:

enter image source here

Let #angleDEF=x, and angleDFE=y#
#=> x+y=180-40=140^@#

Given #EC=AC, => angleEAC=x#
#=> angleECA=180-2x#
Given #CF=BC, => angleFBC=y#
#=> angleFCB=180-2y#

#angleACB=180-(180-2x+180-2y)#
#=2(x+y)-180#
#=2*(140)-180=280-180=100^@#

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