Question: Question 6 (4 points)
a) Determine the value of $x$.
$x$
$18^\circ$
$48m$
b) Determine the measure of $\angle A$ to the nearest degree.
$A$
$3m$
$B$
$7m$
$C$
Show all your work!
Graph shapes:
Top-center: a long, thin triangle with a right angle at the upper-left vertex, $x$ marked on the left side, $18^\circ$ marked near the lower-right vertex, and $48m$ labeled along the bottom side.
Center-left: a right triangle labeled $A$, $B$, $C$ with a right angle at $B$, $AB = 3m$, $AC = 7m$, and $BC$ drawn vertically down to $C$.
1. **Problem Statement:**
We have two right triangles.
(a) Find the length $x$ in the triangle with a right angle at the upper-left vertex, an angle of $18^\circ$ near the lower-right vertex, and the bottom side length $48m$.
(b) Find the measure of $\angle A$ in the right triangle $ABC$ with right angle at $B$, where $AB=3m$ and $AC=7m$.
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2. **Part (a): Find $x$**
- The triangle is right angled at the upper-left vertex.
- The side opposite the $18^\circ$ angle is $x$ (left side).
- The side adjacent to the $18^\circ$ angle is $48m$ (bottom side).
Using the tangent function:
$$\tan(18^\circ) = \frac{\text{opposite}}{\text{adjacent}} = \frac{x}{48}$$
Rearranging to solve for $x$:
$$x = 48 \times \tan(18^\circ)$$
Calculate:
$$x = 48 \times \tan(18^\circ) \approx 48 \times 0.3249 = 15.5952$$
Rounded to two decimal places:
$$x \approx 15.60m$$
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3. **Part (b): Find $\angle A$**
- Triangle $ABC$ is right angled at $B$.
- Hypotenuse $AC = 7m$.
- Side $AB = 3m$.
We want to find $\angle A$.
Using the cosine function (adjacent over hypotenuse):
$$\cos(\angle A) = \frac{AB}{AC} = \frac{3}{7}$$
Calculate $\angle A$:
$$\angle A = \cos^{-1}\left(\frac{3}{7}\right)$$
Calculate the inverse cosine:
$$\angle A \approx \cos^{-1}(0.4286) \approx 64.62^\circ$$
Rounded to the nearest degree:
$$\angle A \approx 65^\circ$$
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**Final answers:**
- (a) $x \approx 15.60m$
- (b) $\angle A \approx 65^\circ$