Answer:
45
Step-by-step explanation:
AEF is a similar triangle to ABC. that means it has the same angles, and the sides (and all other lines in the triangle) are scaled from the ABC length to the AEF length by the same factor f.
now, what is f ?
we know this from the relation of AC to FA.
FA = 12 mm
AC = 12 + 28 = 40 mm
so, going from AC to FA we multiply AC by f so that
AC × f = FA
40 × f = 12
f = 12/40 = 3/10
all other sides, heights, ... if ABC translate to their smaller counterparts in AEF by that multiplication with f (= 3/10).
the area of a triangle is
baseline × height / 2
aABC = 500
and because of the similarity we don't need to calculate the side and height in absolute numbers. we can use the relative sizes by referring to the original dimensions and the scaling factor f.
baseline small = baseline large × f
height small = height large × f
we know that
baseline large × height large / 2 = 500
baseline large × height large = 1000
aAEF = baseline small × height small / 2 =
= baseline large × f × height large × f / 2 =
= baseline large × height large × f² / 2 =
= 1000 × f² / 2 = 500 × f² = 500 ×(3/10)² =
= 500 × 9/100 = 5 × 9 = 45 mm²
When dealing with radicals and exponents, one must realize that fractional exponents deals directly with radicals. In that sense, sqrt(x) = x^1/2
Now, how to go about doing this:
In a fractional exponent, the numerator represents the actual exponent of the number. So, for x^2/3, the x is being squared.
For the denominator, that deals with the radical. The index, to be exact. The index describes what KIND of radical (or root) is being taken: square, cube, fourth, fifth, and so on. So, for our example x^2/3, x is squared, and that quantity is under a cube root (or a radical with a 3). Here are some more examples to help you understand a bit more:
x^6/5 = Fifth root of x^6
x^3/1 = x^3
^^^Exponential fractions still follow the same rules of simplifying, so...
x^2/4 = x^1/2 = sqrt(x)
Hope this helps!
You don't say whether this is a right triangle or not.
Assuming it is a right triangle, then we use the Pythagorean Theorem to determine the length of the hypotenuse:
(hypo) = (length of third side) = √(12^2 + 4^2) = √(144+16) = √160 = 4√10.
This is approx. 12.65 inches. Since this does not match any of the possible answer choices, we'll have to take a different approach to answering this question.
Given that 2 sides of the given triangle are 12 and 4 inches, respectively, we see that the 3rd side has to be longer than 8 inches; otherwise we'd have three line segments on the same line, not forming a triangle.
By this reasoning, 9 inches is the only possible answer that could be correct. With sides 12, 9 and 4 inches, the triangle would be obtuse and appear quite flat, but not be part of a straight line as with a third side of 8.
