Question

triangle ABC is an isosceles triangle in which a b is equals to AC triangle BA is produced to D such that 80 is equals to a b show that angle BCD is a right angle

Answer 1

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Answer 2

in triangle abc,given ab=ac, so angke b=angle c=x now angle bac=180-2x in triangle adc,given ab=ad and therefore ac=ad(ab=ac) let again angle d=angle=acd=x in triangle acd,angle cad=180-(180-2x) =180-180+2x =2x so,2x+x+x=180 4x=180 x=45 now angle dbc=angle dca+angle acb =45+45 =90