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2 years ago

15

Determine the coordinates of the point on the unit circle corresponding to the given central angle. If necessary round your resu

lts to the nearest hundredth 180

1 answer:

Olenka [21]2 years ago

3 0

Answer:

Option A. (-1, 0)

Step-by-step explanation:

In the figure attached,

Circle O is a unit circle (having radius r = 1 unit)

If a point A with central angles = θ, is lying on the circle then the coordinates of the point A will be,

x = r.cosθ

x = 1.cosθ = cosθ

and y = r.sinθ

y = 1.sinθ = sinθ

Therefore, coordinates representing the point A will be (cosθ, sinθ).

As per question the given point A is lying at P (a point having central angle θ = 180°)

Coordinates of point P will be

(x', y') → (cos180°, sin180°)

→ (-1, 0)

Therefore, Option A will be the answer.

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2 years ago

The angle of elevation from me to the top of a hill is 51 degrees. The angle of elevation from me to the top of a tree is 57 deg

julia-pushkina [17]

Answer:

Approximately $101\; \rm ft$ (assuming that the height of the base of the hill is the same as that of the observer.)

Step-by-step explanation:

Refer to the diagram attached.

Let $\rm O$ denote the observer.
Let $\rm A$ denote the top of the tree.
Let $\rm R$ denote the base of the tree.
Let $\rm B$ denote the point where line $\rm AR$ (a vertical line) and the horizontal line going through $\rm O$ meets. $\angle \rm B\hat{A}R = 90^\circ$ .

Angles:

Angle of elevation of the base of the tree as it appears to the observer: $\angle \rm B\hat{O}R = 51^\circ$ .
Angle of elevation of the top of the tree as it appears to the observer: $\angle \rm B\hat{O}A = 57^\circ$ .

Let the length of segment $\rm BR$ (vertical distance between the base of the tree and the base of the hill) be $x\; \rm ft$ .

The question is asking for the length of segment $\rm AB$ . Notice that the length of this segment is $\mathrm{AB} = (x + 20)\; \rm ft$ .

The length of segment $\rm OB$ could be represented in two ways:

In right triangle $\rm \triangle OBR$ as the side adjacent to $\angle \rm B\hat{O}R = 51^\circ$ .
In right triangle $\rm \triangle OBA$ as the side adjacent to $\angle \rm B\hat{O}A = 57^\circ$ .

For example, in right triangle $\rm \triangle OBR$ , the length of the side opposite to $\angle \rm B\hat{O}R = 51^\circ$ is segment $\rm BR$ . The length of that segment is $x\; \rm ft$ .

$\begin{aligned}\tan{\left(\angle\mathrm{B\hat{O}R}\right)} = \frac{\,\rm {BR}\,}{\,\rm {OB}\,} \; \genfrac{}{}{0em}{}{\leftarrow \text{opposite}}{\leftarrow \text{adjacent}}\end{aligned}$ .

Rearrange to find an expression for the length of $\rm OB$ (in $\rm ft$ ) in terms of $x$ :

$\begin{aligned}\mathrm{OB} &= \frac{\mathrm{BR}}{\tan{\left(\angle\mathrm{B\hat{O}R}\right)}} \\ &= \frac{x}{\tan\left(51^\circ\right)}\approx 0.810\, x\end{aligned}$ .

Similarly, in right triangle $\rm \triangle OBA$ :

$\begin{aligned}\mathrm{OB} &= \frac{\mathrm{AB}}{\tan{\left(\angle\mathrm{B\hat{O}A}\right)}} \\ &= \frac{x + 20}{\tan\left(57^\circ\right)}\approx 0.649\, (x + 20)\end{aligned}$ .

Equate the right-hand side of these two equations:

$0.810\, x \approx 0.649\, (x + 20)$ .

Solve for $x$ :

$x \approx 81\; \rm ft$ .

Hence, the height of the top of this tree relative to the base of the hill would be $(x + 20)\; {\rm ft}\approx 101\; \rm ft$ .

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2 years ago

Graph 14x+34y=1 pretty please with a cherry on top!Also thank-you

Svetlanka [38]

To make it much easier, it should be converted to the slope-intercept form
y = mx + b

To do so, 14x + 34y = 1 turns to:
34y = -14x + 1

Divide both sides by 34:
$\frac{34y}{34} = \frac{-14}{34} x + \frac{1}{34}$
Simplified:
$y = \frac{-7}{17} x + \frac{1}{34}$

Answer: $y = -\frac{7}{17} x + \frac{1}{34}$
Here is the graph:

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2 years ago