Respuesta :

as its a isosceles triangle Base angles are equal

  • AB=AC

[tex]\\ \rm\Rrightarrow m<A=m<C[/tex]

[tex]\\ \rm\Rrightarrow m<C=70°[/tex]

Now using angle sum property

[tex]\\ \rm\longmapsto m<A+m<B+m<C=180[/tex]

[tex]\\ \rm\longmapsto 70+70+m<B=180[/tex]

[tex]\\ \rm\longmapsto m<B+140=180[/tex]

[tex]\\ \rm\longmapsto m<B=180-140[/tex]

[tex]\\ \rm\longmapsto m<B=40[/tex]

Answer:

B

Step-by-step explanation:

Since the triangle is isosceles then the 2 base angles are congruent, that is

∠ A = ∠ C = 70° , then

∠ B = 180° - (70 + 70)° = 180° - 140° = 40° → B

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