Question

Brainliest, thanks, and five star if it is correct.

Answer 1

Consider the triangle ADE.
We know that the sum of the three angles of a triangle = 180°

∠AED = 48°
∠DAE = 42°
∠ADE =x

∠AED + ∠DAE +∠x =180°

48°+42°+x° = 180°;  →→90°+x°=180° and x°= 90°
That means that AC is perpendicular to EF