A right triangle with coordinates A (-1,4), B (-1, 8) and C (3, 4) is first rotated 90 degrees counterclockw- then translated 2 units left and 3 units down to form triangle A'B'C'.
What is the measure of angle B'A'C', in degrees, in the resulting figure?

last option

step-by-step explanation:

given that δdef is right and isoceles,

assuming that side df is the hypotenuse means that de an ef are the other 2 sides that intersect at 90° and are of equal length.

because they are of equal length, we can say that they are congruent

because they intersect at 90°, their slopes must be opposite reciprocals.

only the last option satisfies these conditions.