Question 696909
if {{{AB=AC}}} and m< {{{a=100}}}° what is the measure of m < {{{b}}} in degrees 

if {{{AB=AC}}}...=> you have an isosceles triangle and m < {{{b}}} is equal to m < {{{c}}}

since the three angles in triangle always add to {{{180}}}°, we have

{{{a+b+c=180}}}°........since m < {{{b}}} = m < {{{c}}}


{{{100+b+b=180}}}°

{{{2b=180-100}}}°

{{{2b=80}}}°

{{{b=80/2}}}°

{{{b=40}}}° and m < {{{c=40}}}° too