In the following figure find #m/_x#?

enter image source here

3 Answers
Jan 9, 2018

Image reference...
Answer#=36^@#

Explanation:

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#color(red)(X = 36^0#

Explanation:

#/_(BAC) = /_(ACD) = /_(ABC) = X# as

#color(red)(AD = DC = BC)#

#/_(BDC) = /_(DAC) + /_(DCA) = 2X#

Exterior angle = sum of the interior opposite angles

#/_(BDC) = /_(BCD) = 2X# as

#color(red)(BC = BD)#

In triangle BDC,
#/_(DBC) + /_(BCD) + /_(BDC) = 180^0#

I. e. #X + 2X + 2X = 180^0#

#X = 180 / 5 = 36^0#

#color(red)(X = 36^0#

Jan 9, 2018

#m/_x=36^@#

Explanation:

Let us name the points in the diagram as follows:
enter image source here

As #DeltaBCD# is isoscoles triangle, we have

#m/_DCB=m/_DBC=x#

and as exterior angle of a triangle is always equal to sum of intereor opposite angles

#m/_ADC=x+x=2x#

Again as #DeltaADC# is isoscels triangle abd hence #m/_ACD=m/_ADC=2x#

and hence #m/_A=180^@-2x-2x=180^@-4x#

Also #m/_ACB=m/_DCB+m/_ACD=x+2x=3x#

Now as #AC=BC# we have #m/_A=m/_B=x# and hence

in #DeltaABC#, the three angles are #x,x# and #3x# and we have

#x+x+3x=180^@# or #5x=180^@# or #x=36^@#