Question 1209961: Find the area of the kite
I got the answer 156.16cm
https://ibb.co/ch1SdtSh
https://ibb.co/gM0Lsps7 Found 3 solutions by Edwin McCravy, ikleyn, mccravyedwin:Answer by Edwin McCravy(20055) (Show Source):
You don't need all those angles you show in the 2nd link. You just need to
learn about two kinds of special right triangles, the 45-45-90 right triangle
and the 30-60-90 right triangle. That's what this kite is made up of, 2
of each. There are two 30-60-90 right triangles on the left, and two 45-45-90
right triangles on the right:
You should learn the following information about these
two special right triangles. They occur very often.
The sides of the standard 45-45-90 right triangle:
The two legs are 1 unit long each.
The hypotenuse is units long.
The triangle is both a right triangle and also an isosceles triangle.
The sides of the standard 30-60-90 right triangle:
The shorter leg is 1 unit long.
The longer leg is units long.
The hypotenuse is 2 units long.
Again, I emphasize that you need to learn the above information about
those two standard right triangles. They occur often in these
geometry problems.
Let the longer leg of your 30-60-90 right triangle be x.
You are given that the shorter leg of the 30-60-90 triangle
on the upper left is given as 8 cm.
So make the proportion:
cross-multiply:
So the longer leg of each of the 30-60-90 right triangles on the left
have base and given height 8. So the area of each of
those two 30-60-90 right triangles is:
Now do the same for each of the two 45-45-90 right triangles on the right.
There's less work to do here, because you know that in a 45-45-90 triangle
both legs are the same length. So we know that the base and height are
the same length. So they are both 8 cm.
Since the kite is made up of two 30-60-90 right triangles plus
two 45-45-90 right triangles the total area is:
and if you like, you can factor out 64, and get
That's about
Edwin
Two triangles with the angles of 45 degrees form a square with the side of 8 cm,
if to attach them hypotenuse to hypotenuse.
So, the total area of these two triangles is = 64 cm^2.
The great triangle on the left is the equilateral triangle with the side length a = 16 cm,
since all three its angles are 60 degrees each.
The area of such a triangle is
= = = cm^2.
Therefore, the total area of the given kite is
64 + = = 174.85 square centimeters approximately. ANSWER
Solved.
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Equilateral triangles come very often in geometry problems.
Therefore, it is useful to know this formula for their area, ,
via their side length " a ", in order for do not derive it every time from scratch.
Here is a link to a good lesson on the special right triangles:
https://flexbooks.ck12.org/cbook/ck-12-precalculus-concepts-2.0/section/4.3/primary/lesson/special-right-triangles-pcalc/
Edwin