Question

Gloria's teacher asks her to draw a triangle with a 90° angle and a 42° angle.How many unique triangles can Gloria draw that meet her teacher's requirements?AOne unique triangle can be drawn because the third angle must measure 48º.BNo unique triangle can be drawn because the teacher only gave the measures of two angles.СInfinitely many unique triangles can be drawn because the side lengths of the triangles can be different sizes.DThere is not enough information to determine how many unique triangles can be drawn.

Answer 1

Sum of angles in a triangle must be equal to 180°

So, since one of the angle measures 90° and the other is 42°, then

90 + 42 + y = 180°, where y is the third angle

So, 132 + y = 180

y = 180 - 132 = 48°.

Therefore, one unique triangle can be drawn because the third angle must measure 48º.

Option A is the correct answer.