Question

In triangle ABC, angle A is 75o and angle B is 20o. Select the triangle that is similar to triangle ABC.

a Triangle DEF where angle D is 75o and angle E is 20o.
b Triangle DEF where angle D is 20o and angle F is 85o.
c Triangle DEF where angle D is 85o and angle E is 20o.
d Triangle DEF where angle D is 20o and angle E is 75o.

Answer 1

A.
`\triangle`DEF where
`\angle D = 75^(\circ)` and
`\angle E = 20^(\circ)`.

Explanation:

At first we must keep in mind that two triangles are similar when they have same angle configuration, that is, each pair of angles is congruent. If
`\triangle`ABC and
`\triangle`DEF, then
`\angle A \equiv \angle D` and
`\angle B \equiv \angle E`. Hence,
`\angle D = 75^(\circ)` and
`\angle E = 20^(\circ)`.

In a nutshell, correct answer is A.