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
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 lines are perpendicular.
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