Question

When the angle of elevation of the sun is 64°, a pole that is tilted at an angle of 19° directly away from the sun casts a shadow 21 feet long on level ground. approximate the length of the pole to the nearest foot?

Answer 1

Angles at a point make 180° at a straight line.
Lx = 180° - (90+90)
Lx is 70°
Lx = 180° -(64+71)
= 180° - 13J°
= 45°
By using sine law
21/siny = length of pole/ sin 64
∴Length of pole = 21 sin 64/sin u5 = 26.69
Then the length of pole = 27ft

Answer 2

Answer:

Length of the pole is 27ft. ( rouding up to the nearest foot)

Explanation:

To solve this problem you need to understand that the the shadow cast by the pole on the ground connected to the pole itself and to the imaginary line of sun light forms a triangle with 3 different angles, please see the drawing to a better understanding.

* The sum of the internal angles of any triangle must be 180° then;

α: angle of the elevation of the sun= 64°

angle of the pole to the ground= (90-19)= 71°

β = 180 - ( 64+71) = 45°

*To find the length of the pole we can use the law of Sines;

|BC| / sin (α) = |AC| / sin (β)

|BC|= Length of the pole

|AC|= shadow of the pole on the ground which is known to be 21 ft

|BC| / sin (64°) = 21 / sin (45°)

|BC|= 21 x [sin (64°)/ sin (45°)]

|BC|= 21 x 1.27≅ 26.67 ft