1.
Let the measures of the triangle be 40°, a and b.
2.
a and b are in the ratio 3:4, so let a=3t and b=4t.
(check: a:b = 3t: 4t = 3:4)
3.
So the measures of the angles are 40°, 3t and 4t.
4.
the sum of the measures of the interior angles of any triangle is 180°,
thus :
40° + 3t + 4t =180°
40°+7t=180°
7t=180°-40°
7t=140°
t=140°/7=20°
5.
thus the measures of the angles are:
a=3t=3*20°=60°
and
b=4t=4*20°=80°.
Answer: 60° and 80°