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Trigonometry
7. An inclined iron rod AB of length (b) Find the horizontal distance
15 m has a wire tied at A so as to be travelled correct to the nearest
used to lift loads at point C which is metre.
11 m from B as shown in the following
diagram. Find the angle that the iron 11. The depth of a straight underground
rod makes with this wire. mine tunnel is 240 m. The end of the
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mine tunnel is 200 m horizontally
from the entrance. What angle does
the tunnel make with the horizontal?
12. A technician is designing a ramp to
load a heavy machine onto a platform. Mathematics for Secondary Schools
The platform is 1.5 m high and the
ramp needs to be at an inclination of
20° to ensure safe loading. Determine
8. A 30 cm long pendulum swings back the length required and the horizontal
and forth through an angle of 20° on distance it will cover.
each side as shown in the following
figure. How high does the lower end The angles of elevation and depression
of the pendulum rise?
When observing an object, you can either
observe it horizontally if the object and line
of sight are at the same level. Observing
it downward if the observer is above the
object and observing it upwards if the
observer is below the observed object.
To experience these scenarios, engage in
Activity 8.5.
Activity 8.5: Studying different angles
9. The diagonal of a rectangle makes formed when observing
an angle of 39° with the longer side. objects
Find the width of the rectangle if its 1. At your place, choose an object to
length is 50 cm. observe which is at the same level
10. A car which was originally at sea as your eyes. For instance, a person
level traveled a distance of 400 m whose height is the same as yours
uphill inclined at an angle of 28° to and you look at his eyes.
the horizontal. 2. In the second scenario, observe
(a) Find the height the car attained an object which you need to look
above sea level after travelling downward. For instance, looking at a
400 m. coin on the floor while standing.
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MATHEMATIC F2 v5.indd 185
