Answer :
Isosceles triangle , 2 base angles are equal .sum of all angles of a triangle = 180°
180°-2 ( base angles )
a) 180°-2(40°)
=180°-80°
= 100°
b) 180°-2(87°)
= 180°-174°
=6°
c) 180°-2(15°)
= 180°-30°
= 150°
d) 180°-2(79°)
=180°-158°
= 22°
180°-2 ( base angles )
a) 180°-2(40°)
=180°-80°
= 100°
b) 180°-2(87°)
= 180°-174°
=6°
c) 180°-2(15°)
= 180°-30°
= 150°
d) 180°-2(79°)
=180°-158°
= 22°