We are asked to find the missing elements (sides and angles), the perimeter, and the area of the given right triangles. a) We have a right triangle with side $a = 45 m$ and angle $C = 25^\circ$. We need to find side $b$, side $c$, angle $B$, the perimeter, and the area. b) We have a right triangle with sides $5 km$ and $12 km$. We need to find the hypotenuse $x$, and then calculate the perimeter and the area.

GeometryRight TrianglesTrigonometryPythagorean TheoremPerimeterAreaAngles
2025/4/28

1. Problem Description

We are asked to find the missing elements (sides and angles), the perimeter, and the area of the given right triangles.
a) We have a right triangle with side a=45ma = 45 m and angle C=25C = 25^\circ. We need to find side bb, side cc, angle BB, the perimeter, and the area.
b) We have a right triangle with sides 5km5 km and 12km12 km. We need to find the hypotenuse xx, and then calculate the perimeter and the area.

2. Solution Steps

a)
Since the sum of angles in a triangle is 180180^\circ and we have a right triangle, we know that A=90A = 90^\circ. Thus, B=1809025=65B = 180^\circ - 90^\circ - 25^\circ = 65^\circ.
To find bb, we use the sine function:
sin(C)=casin(C) = \frac{c}{a}
Therefore c=asin(C)c = a * sin(C). Then c=45sin(25)=450.422619.02mc = 45 * sin(25^\circ) = 45 * 0.4226 \approx 19.02 m
To find bb, we use the cosine function:
cos(C)=bacos(C) = \frac{b}{a}
Therefore b=acos(C)b = a * cos(C). Then b=45cos(25)=450.906340.78mb = 45 * cos(25^\circ) = 45 * 0.9063 \approx 40.78 m
Perimeter P=a+b+c=45+40.78+19.02=104.8mP = a + b + c = 45 + 40.78 + 19.02 = 104.8 m
Area A=12bc=1240.7819.02387.83m2A = \frac{1}{2} * b * c = \frac{1}{2} * 40.78 * 19.02 \approx 387.83 m^2
b)
We use the Pythagorean theorem to find the hypotenuse xx:
x2=52+122=25+144=169x^2 = 5^2 + 12^2 = 25 + 144 = 169
x=169=13kmx = \sqrt{169} = 13 km
Perimeter P=5+12+13=30kmP = 5 + 12 + 13 = 30 km
Area A=12512=30km2A = \frac{1}{2} * 5 * 12 = 30 km^2

3. Final Answer

a)
B=65B = 65^\circ
c19.02mc \approx 19.02 m
b40.78mb \approx 40.78 m
P104.8mP \approx 104.8 m
A387.83m2A \approx 387.83 m^2
b)
x=13kmx = 13 km
P=30kmP = 30 km
A=30km2A = 30 km^2

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