Which of the following is an acute angle?

Which of the following is a acute disease ?

Which of the following pairs of angles are supplementary angles?

Two particles are projected in air with speed u at angles theta_(1) and theta_(2) (both acute) to the horizontal, respectively. If the height reached by the first particle is greater than that of the second, then which one of the following is correct ?

Classify the following angles into acute, right, obtuse and straight angles: 40^@,140^@ , 90^@ 210^@ 44^@ 215^@ 345^@ 125^@ 10^@ 120^@ 89^@ 270^@ 30^@ 115^@ 180^@ .