a right angle triangle has a right angle in it, whereas a traingle is the extremely general term for an object with three sides
D.Acute
There are 90 degrees in a left angle as there are in a right angle but the term 'left angle' is rarely used
An acute angle is a geometry term that refers to an angle that is less than 90 degrees. If it is 90 degrees it is a right angle, and if it is more than 90 it is obtuse.
Landing
The lines are perpendicular.
A four-sided shape with one right angle is a quadrilateral. There is no more specific term, unless it has more than one right angle or has equal sides.
The term of Latin in right angle is angulus rectus; here rectus means "upright", referring to the vertical perpendicular to a horizontal base line."Right" has other meanings, apart from the opposite of "left". I suspect that the ethymology here is more like a "correct" angle.
I have never come across the term "blunt" angle. The rays of an angle always meet at a point and there is no rounding of these rays so the only interpretation that I can put on a blunt angle is that it is an obtuse angle. IF that is the case, (and sorry if I have misunderstood), then a right angle is smaller.
Perpendicular.
No, it isn't. The term Hypotenuse is associated with right triangles. It is the longest side of the triangle, opposite the right angle.
a right angle is a right angle