7 A missile is projected from a point \(O\) on horizontal ground with speed \(175 \mathrm {~ms} ^ { - 1 }\) at an angle of elevation \(\theta\). The horizontal lower surface of a cloud is 650 m above the ground.
- Find the value of \(\theta\) for which the missile just reaches the cloud.
It is given that \(\theta = 55 ^ { \circ }\).
- Find the length of time for which the missile is above the lower surface of the cloud.
- Find the speed of the missile at the instant it enters the cloud.