Question

angle ABC=69° angle ACB=31° find angle BDC.​

Answer 1

angle BDC is 80 degree by angle sum property

Answer 2

angle ABC+ACB+BDC=180 ...sum of measures of all angles of triangle is 180°

hence,

angle BDC=80°after calculation .

69+31+angleBDC=180

100-180=BDC

BDC=80°