A trapezoid has a height of 6 feet. The measures of the bases are 12 units and 18

Mathematics

1 answer:

Alik [6]3 years ago

8 0

The area of this trapezoid is 90 square feet.

<h3>Explanation : </h3>

Before we know the answer, let's we know the formula first. The formula for count the area of trapezoid is :

$\boxed {\bold {A = \frac {(a+b) \times h}{2}}}$

If :

A = area of trapezoid
a = bottom bases of trapezoid
b = top bases of trapezoid
h = height of trapezoid

Okay, let's we count its :

We know that :

a = bottom bases of trapezoid = 18 feet
b = top bases of trapezoid = 12 feet
h = height of trapezoid = 6 feet

Question : A = area = ... ?

Answer :

$A = \frac {(a+b) \times h}{2} \\ A = \frac {(12+18) \times \cancel6}{\cancel2} \\ A = 30 \times 3 = 90 \: {ft}^{2}$

Subject : Mathematics

Keyword : Count The Area of a shape

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The surface are I cannot find

Ilia_Sergeevich [38]

check the picture below.

so the triangular prism is really just 3 rectangles and 2 right-triangles,

now, we know the base of one of the triangles is 2.6, what's its height?

since it's a right-triangle, we can simply use the pythagorean theorem to get "h".

$\bf \textit{using the pythagorean theorem}
\\\\
c^2=a^2+b^2\implies \sqrt{c^2-a^2}=b
\qquad
\begin{cases}
c=\stackrel{hypotenuse}{5.2}\\
a=\stackrel{adjacent}{2.6}\\
b=\stackrel{opposite}{h}\\
\end{cases}
\\\\\\
\sqrt{5.2^2-2.6^2}=h\implies 4.5\approx h$

so, we can now, simply get the area of both of the triangles and the three rectangles and sum them up, and that's the area of the triangular prism.

$\bf \stackrel{two~triangles}{2\left[ \cfrac{1}{2}(2.6)(4.5) \right]}~~+~~\stackrel{rectangle}{(2.6\cdot 4.3)}~~+~~\stackrel{rectangle}{(4.3\cdot 3.9)}~~+~~\stackrel{rectangle}{(4.3\cdot 5.2)}
\\\\\\
11.7+11.18+22.36\implies \blacktriangleright 45.24 \blacktriangleleft$