# CBSE Class 10-Mathematics: Chapter –9 Some Applications of Trigonometry Part 13

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**Question 23:**

The angle of elevation of a jet-plane from a point P on the ground is . After a flight of 15 seconds the angle of elevation (change to ). If the jet plane is flying at a constant height of , find the speed of the jet plane in km/hour.

**Answer:**

Let A be the point on the ground E is the position of aeroplane such that and

C is the position of plane after seconds

In right

In

Distance

Speed

**Question 24:**

A pole high is fixed on the top of a tower. The angle of elevation of the top of pole observed from a point A on the ground is and the angle of depression of the point A from the top of the tower is . Find the height of the tower. (Take )

**Answer:**

In

In

**Question 25:**

From a window high above the ground in a street. The angles of elevation and depression of the top and foot of another house on the opposite side of the street are respectively. Show that the height of the apposite house is .

**Answer:**

Suppose

Then,

In

In

Then

Height of another house