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Mathematics 7 Online
OpenStudy (firejay5):

Find the area of each figure. When an answer is NOT a whole number, round to the nearest tenth.

OpenStudy (firejay5):

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OpenStudy (firejay5):

@surjithayer

OpenStudy (firejay5):

@timo86m @whpalmer4

OpenStudy (abb0t):

The 45º-45º should give you a clue about the triangle given. Does that ring a bell?

OpenStudy (whpalmer4):

Here's another hint: in a right triangle, one of the sides going into the right angle will serve as an altitude or height. The other will serve as a base. Area of a triangle is \[A = \frac{1}{2}bh\] where \(b\) is the length of the base, and \(h\) is the height or altitude

OpenStudy (firejay5):

is 14 * sqrt 2 the base or height

OpenStudy (whpalmer4):

Does the side labeled with that go into the little right triangle angle box?

OpenStudy (whpalmer4):

Has anyone ever pointed out to you that in a 45/45/90 triangle, such as the one we have here, the hypotenuse is always \(\sqrt{2}\) times the length of either of the two sides?

OpenStudy (firejay5):

what if the their isn't sides

OpenStudy (firejay5):

14 * sqrt 2 * sqrt 2 = 56m^2 <--- ha ha I think that's wrong! :D

OpenStudy (whpalmer4):

how can you have a triangle without sides?

OpenStudy (firejay5):

that's what my problem is

OpenStudy (firejay5):

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OpenStudy (whpalmer4):

okay, that's a right triangle, and you know the length of the hypotenuse, and it's not just any right triangle, it's an isosceles triangle because the two angles are equal. What does that imply about the lengths of the unknown sides?

OpenStudy (whpalmer4):

Come on, man, you've done a number of problems like this now, aren't you picking up on the patterns?

OpenStudy (firejay5):

I got 56m^2

OpenStudy (whpalmer4):

show me your work

OpenStudy (firejay5):

\[14\sqrt{2} * \sqrt{2} = 28m^2\] not 56m^2

OpenStudy (whpalmer4):

Where did you get those numbers?

OpenStudy (firejay5):

from the figure where else duh

OpenStudy (firejay5):

14 * sqrt 2 * sqrt 2 <--- as the hypotenuse = 28m^2

OpenStudy (whpalmer4):

can you please go read what I wrote earlier about the base and the height?

OpenStudy (firejay5):

yes, but there are no sides though HELLO??? How else will I solve it

OpenStudy (whpalmer4):

duh. it's an isosceles triangle. use the Pythagorean theorem.

OpenStudy (firejay5):

I did Pythagorean Theorem and I got sqrt 14. a & b = x c = 14 times sqrt 2

OpenStudy (whpalmer4):

\[c = 14\sqrt{2}\]\[c^2=\]?

OpenStudy (firejay5):

wait stop right there where a & b

OpenStudy (whpalmer4):

no need for a and b. I told you what c is. What is the value of c^2?

OpenStudy (whpalmer4):

c*c

OpenStudy (firejay5):

28

OpenStudy (whpalmer4):

\[14\sqrt{2}*14\sqrt{2} = 28\]?!?

OpenStudy (whpalmer4):

\[\sqrt{2} \approx 1.414\]\[14*1.414\approx 20\]\[20*20 = 400\] Missed it by a county mile!

OpenStudy (firejay5):

explain how you got that answer

OpenStudy (whpalmer4):

what is \[\sqrt{2}*\sqrt{2}\]?

OpenStudy (firejay5):

How is 14\[14\sqrt2 * 14\sqrt2 = 28 ---> 392\]

OpenStudy (firejay5):

I got 392 not 28 if you multiplied 14 * sqrt 2 twice

OpenStudy (whpalmer4):

Yes, c^2 = 392. Now, we know (at least I do) that a = b because this is an isosceles triangle because the two angles other than the right angle are equal. So in the Pythagorean theorem: \[a^2+b^2=392\]\[a^2+a^2=392\]\[2a^2=392\]Solve for the value of \(a\)

OpenStudy (firejay5):

anyways x = 14

OpenStudy (firejay5):

is that the height

OpenStudy (whpalmer4):

that is the height, and it is also the base.

OpenStudy (firejay5):

why is that?

OpenStudy (firejay5):

98m^2

OpenStudy (whpalmer4):

|dw:1392264892920:dw|

OpenStudy (firejay5):

I got 98m^2 is that right

OpenStudy (whpalmer4):

yes. (1/2)*14*14 = 98. if the original measurements are in meters, then m^2 is the right unit.

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