9. A and [tex]B[/tex] are two points on level ground both due south of a flagpole. The angle of elevation of the top of the flagpole is [tex]60^{\circ}[/tex] from [tex]A[/tex] and [tex]45^{\circ}[/tex] from [tex]B[/tex]. If [tex]A[/tex] is [tex]2 \, m[/tex] from the foot of the flagpole, find [tex]\mid AB \mid[/tex].



Answer :

Alright, let's solve the given problem step by step.

Given:
1. Angle of elevation from point [tex]\( A \)[/tex] to the top of the flagpole: [tex]\( 60^\circ \)[/tex]
2. Angle of elevation from point [tex]\( B \)[/tex] to the top of the flagpole: [tex]\( 45^\circ \)[/tex]
3. Distance from [tex]\( A \)[/tex] to the foot of the flagpole: 2 meters

We need to find the height of the flagpole [tex]\( (h) \)[/tex], the distance from point [tex]\( B \)[/tex] to the foot of the flagpole [tex]\( (d_B) \)[/tex], and the distance between points [tex]\( A \)[/tex] and [tex]\( B \)[/tex] [tex]\( (AB) \)[/tex].

1. Finding the height of the flagpole [tex]\( (h) \)[/tex]:

Let [tex]\( h \)[/tex] be the height of the flagpole.

From the point [tex]\( A \)[/tex], with an angle of elevation of [tex]\( 60^\circ \)[/tex], we can use the tangent function:
[tex]\[ \tan(60^\circ) = \frac{h}{d_A} \quad \text{where \( d_A = 2 \)} \][/tex]

We know [tex]\( \tan(60^\circ) = \sqrt{3} \)[/tex], so:
[tex]\[ \sqrt{3} = \frac{h}{2} \][/tex]

Solving for [tex]\( h \)[/tex]:
[tex]\[ h = 2 \sqrt{3} \][/tex]

Approximating the value:
[tex]\[ h \approx 3.464 \text{ meters} \][/tex]

2. Finding the distance from point [tex]\( B \)[/tex] to the foot of the flagpole [tex]\( (d_B) \)[/tex]:

From the point [tex]\( B \)[/tex], with an angle of elevation of [tex]\( 45^\circ \)[/tex], we again use the tangent function:
[tex]\[ \tan(45^\circ) = \frac{h}{d_B} \][/tex]

We know [tex]\( \tan(45^\circ) = 1 \)[/tex], so:
[tex]\[ 1 = \frac{h}{d_B} \][/tex]

Solving for [tex]\( d_B \)[/tex]:
[tex]\[ d_B = h \][/tex]

Substituting the value of [tex]\( h \)[/tex]:
[tex]\[ d_B = 3.464 \text{ meters} \][/tex]

3. Finding the distance between points [tex]\( A \)[/tex] and [tex]\( B \)[/tex] [tex]\( (AB) \)[/tex]:

The distance [tex]\( AB \)[/tex] is the difference between the distances from the foot of the flagpole to points [tex]\( A \)[/tex] and [tex]\( B \)[/tex]:
[tex]\[ AB = d_A - d_B \][/tex]

Substituting the values:
[tex]\[ AB = 2 - 3.464 \][/tex]

Approximating the value:
[tex]\[ AB \approx -1.464 \text{ meters} \][/tex]

Now, summarizing the results:

- Height of the flagpole [tex]\( h \approx 3.464 \)[/tex] meters
- Distance from point [tex]\( B \)[/tex] to the foot of the flagpole [tex]\( d_B \approx 3.464 \)[/tex] meters
- Distance between points [tex]\( A \)[/tex] and [tex]\( B \)[/tex] [tex]\( AB \approx -1.464 \)[/tex] meters

Please note that the difference being negative indicates that point B is actually further behind the flagpole compared to point A.