A triangular plot of land has sides of lengths 420 feet, 330 feet, and 180 feet. Approximate the smallest angle between the sides. The choices are rounded to the nearest degree.
A. 30 degree
B. 27 degree
C. 22 degree
D. 24 degree

Respuesta :

Answer:

D. 24 degree

Step-by-step explanation:

Sides of the triangle are

a = 330 ft

b = 180 ft

c = 420 ft

From cosine rule we have

[tex]\angle A=\cos^{-1}(\dfrac{b^2+c^2-a^2}{2bc})\\ =\cos^{-1}(\dfrac{180^2+420^2-330^2}{2\times180\times 420})\\ =48.65^{\circ}[/tex]

[tex]\angle B=\cos^{-1}(\dfrac{a^2+c^2-b^2}{2ac})\\ =\cos^{-1}(\dfrac{330^2+420^2-180^2}{2\times 330\times 420})\\ =24.17^{\circ}[/tex]

[tex]\angle C=\cos^{-1}(\dfrac{a^2+b^2-c^2}{2ab})\\ =\cos^{-1}(\dfrac{330^2+180^2-420^2}{2\times 330\times 180})\\ =107.19^{\circ}[/tex]

The smallest angle in the triangle is [tex]\angle B=24.17^{\circ}[/tex].

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