Question

What is the perpendicular adjacent sides in the triangle

Answer 1

adjecent basically means "next to" and perpindicular is meeting at an right angle (90 degrees) so squares have them and right angle triangles do to.

Answer 2

"Adjacent" means next to each other. "Perpendicular" means at an angle of 90 degrees.
Rectangles (this includes squares) have adjacent perpendicular sides. So do right triangles.