What is obtuse angle ?

Seg XZ is a diameter of a circle. Point Y lies in its interor. How many of the followint statements are true? (1) It is a not possible that /_XYZ is an acute angle. (2) /_XYZ can't be a right angle (3) /_XYZ is an obtuse angle. (4) Can't make a dfinite statement for measure of /_XYZ

What is torsion angle or dihedral angle ?

A ray of light strikes the glass slab at an angle of 50^@ .What is the angle of incidence?

What is the angle between velocity vector and acceleration vector in unitorm circular motion ?

A ray of light falls on a glass plate of refractive index mu=1.5 . What is the angle of incidence of the ray if the angle between the reflected and refracted rays is 90^@ ?

What is mean by angle of contact ? Explain why it is accute in case of water and glass and obtuse in case of mercury and glass.

State whether the following statements are true or false : An acute angle and an obtuse angle can make a pair of supplementary angles.