How to find the radius of a circle of the area?
in
I have a math problem that I dont remember how to do. I have to find the radius of a circle whose area is 121pi cm^2
Can u show me how to do it please?
Answer:
Area is given by:
A = pi*r^2
We know the area, so plug it in and solve for r.
121pi cm^2 = pi*r^2
//Divide both sides by pi
121cm^2 = r^2
//Square root both sides
sqrt(121cm^2) = sqrt(r^2)
11cm = r
Hope that helps.
How to use geometric principles to determine how a Ferris Wheel is stable?
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I'm doing a project where I need to determine how a Ferris Wheel is stable using geometric principles. I'm finding some sources, but I need a few more to prove this. If anybody happens to know a source, or if you have some knowledge in this, I would be very grateful if you shared this with me. Thank you!
Answer:
Make sure you understand these
http://www.physics.orst.edu/~mcintyre/smile/basics.pdf
I don't know where you can get practical information about ferris wheels though.
How to show an quadratic equation is positive for all values of x?
in
I have been given an quadratic equation to complete the square, x² - 14x + 55 in the form (x - a)² + b
I did that, and had (x - 7)² + 6 where then my a = 7 and b = 6 right?
Then the question asks to show that x² - 14x + 55 is positive for all values of x. I have no idea what it means and how to show that.
Answer:
So the question is saying show that it doesn't matter what number you choose x to be, x² - 14x + 55 will always give you a positve number.
You've shown x² - 14x + 55 = (x - 7)² + 6
No matter what x is (x - 7)² is positive (or zero) because even if (x - 7) is negative a negative squared has to be positive ( -ve x -ve = +ve).
Then if you add 6 it's definitly postive now, even if (x - 7) was zero you've added 6.
How to tell if a function is even or odd?
in
Here is the question I am stuck on:
f(x) is a function that generates the ordered pairs (0,0), (1,7), and (2,-3)
If f(x) is an odd function, what are the coordinates of two other points found on the graph f(x)?
Help is much appreciated!
Answer:
http://www.purplemath.com/modules/fcnnot3.htm
How to find the perimeter of a triangle given its angles and area?
in
The angles of an isosceles triangle are 150, 15, 15. If the area is 9 square feet, what is the perimeter of the triangle?
I know I should do something with law of sines or law of cosines, but i'm totally stuck.
Answer:
A = (abSinC)/2
9 = (a * a * Sin 150)/2
a²Sin150 = 18
a² = 36
[ a = 6 ft. ]
a/SinA = c/SinC
6/Sin(15) = b/Sin(150)
c = [ 6 * Sin(150) / Sin(15) ]
[ c ≃ 11.6 ft. ]
P = a + b + c
P ≃ 6 + 6 + 11.6
[ Perimetre ≃ 23.6 ft. ]
Hope this helps
Feel free 2 email me if u have any more questions !!
how to find the missing height of a trapazoid when the area is also missing?
in
I know the formula to find missing dimensions, but both the area and perpendicular height are missing! The bases are 23 and 36.5 and the tilted sides are 32!
Answer:
The sides and part of the longer base (half of the difference of both bases) together with the unknown height form a right triangle.
(36.5 - 23) / 2 = 6.75
6.75^2 + h^2 = 32^2
h^2 = 32^2 - 6.75^2
h = sqrt(32^2 - 6.75^2) = 31.28
How to figure out the perimeter of irregular shapes?
in
I have a lot of irregular shapes in my math project so how would I calculate the area for an irregular shape and the perimeter.
Answer:
try to cut them into squares/ triangles or any other shapes that you can work with easily. same goes with perimeter
How to avoid common error in mathematics?
in
Hi, I am currently studying AS Level for pure maths and prepared quite well. I understood concepts and solving problems but when I check my answers, 50% of it got wrong because of common error like forgot to put/write or add/change sign etc. I'd like to know what would help me avoid these common error and don't want it to happen after tomorrow on 8th of May. My exam is on the 8th of May.
Answer:
I've been through the same thing in my pure maths and further maths papers. My problem was that when I have been doing practice papers I didn't bother to check my mistakes at the end. So when it came to the actual exam and checking through my paper at the end, I wasn't very good at spotting errors. It's important to practice error spotting. It would be hard to avoid making errors completely but just always try to keep your concetration solely on the question.
Good luck with your exam :)
How to you find the angle to the nearest degree?
in
They gave me a triangle and two sides and one angle. I found the last side, but do you find the rest of the angles ? If you do , what do you do after that ? By the way I have a graphing calculator . It's the TI-83 plus, if anyone has it can you show me how to put it in?
Answer:
...you need to use "law of sines" and/or "law of cosines !"
Provide a diagram or more specific information about the given sides and angles...
How did you "find" the last side ?
More information required...
@ß
how to draw a prism that has a volume of 30m3?
in
I need to know the dimensions of a pyramid that has the volume of 30m3. Thank you.
Answer:
http://en.wikipedia.org/wiki/Pyramid_%28geometry%29
volume(V) of a pyramid is volume(V) = (1/3)*base(B)*height(H)
given V = 30m^3 ; choose a height or base area ; just one or the other tho ;
(base = length(L) * width(W) ;
lets choose the height to be 10m , then ;
V = (1/3)*B*H can be rearranged to get B = V/[(1/3) * H] = 30m^3/[(10/3)m] = 9m^2
if the base is square then the length(L) and width(W) are the same and since area(A) of a rectangle(or square) is A = L * W (for a square A = L^2)
given A = L^2 then L = sqrt[A] = sqrt[9m^2] = 3m
so the dimentions "could" be ; base 3m wide , 3m long , 10m high ;
there are infinite solutions!
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