PLEASE HELP ME OKT I DONT UNDERSTAND

See below.

Step-by-step explanation:

5a)

In an isosceles triangle, the angles opposite the congruent sides are congruent.

m<A = 40 deg

m<B = 40 deg

m<A + m<B + m<C = 180

40 + 40 + m<C = 180

m<C = 100 deg

5b)

In a right triangle, one angle is a right angle.

m<A = 40 deg

m<B = 90 deg

m<A + m<B + m<C = 180

40 + 90 + m<C = 180

m<C = 50 deg

(a) the volume of the cone is 20/3 in3

hence, option a is correct.

b

step-by-step explanation: