Any maths wizards on here please? Updated

nomoneytoday

Maybe he should lookup, "Some Officers Have Coaches and Horses to order about"

It gives the angles and ratios to work it out

SIN = Opposite / Hypotenuse
COS = Adjacent / Hypotenuse
TAN = Opposite / Adjacent

bap98189

You can't unless you make an additional measurement. You could have a squat pyramid where h is very small or a very long pyramid where h is very large - both would still be square-based pyramids.

You need to measure either the length of long side (from the vertex to the corner) or measure the angle the long side makes with the base. Without one of those two measurements you cannot calculate the height.

laurel7172

I agree. You need another piece of information: either the length of the sloping sides or their angle. Are you sure it isn't disguised in the question text, perhaps as a ratio? Does it say that ALL the sides are the same length?

shiny76

This question would appear to be similar but gives the length of the slant (so perhaps we're missing necessary info)...

http://www.bbc.co.uk/schools/gcsebitesize/maths/geometry/pythagoras3drev1.shtml

claire21

Yes there's defiantly more of a clue in the question then, there was a previous line and he said that there must be a reason for that, it wasn't another measurement that related to this though, it talked about another pyramid and gave two measurements in that example.

I now know I have given you only half a question and will come back when he logs into mymaths later.

I bet it's gonna be so easy when you have the full question lol

deselby

So, you'll need to calculate the diagonal across the square base. If, for example, the length of the square is 4cm, then if you divide the square into two right-angled triangles, you can use Pythagoras to find that the length would be the square root of 32. Half this, and you'll have the base of a new right-angled triangle, this time with vertices at one of the base corners, the tip of the pyramid and the centre of the base.

Depending on the question, to work out the height of the pyramid, you will either be given the angle of elevation (the angle from the base towards the tip of the pyramid) or the length of the side. I suppose technically, you might be given the height of the triangle on the side, but in my experience, you wouldn't see too many questions like that.

If you're given the angle of elevation, you have the adjacent length already (the square root of 32, divided by 2), and would need to find the opposite side, giving us tan-1 of the angle = x / root 32 divided by 2. That is, tan TO THE POWER OF -1, or inverse tan. This is normally done by using the shift button and then pushing tan.

Alternatively, if you're given the length of the side, you would have to square this figure, and then subtract (root 32 divided by 2) squared. Find the square root of this for your answer!

Lastly, I would suggest you do this all on the calculator like this, using the ANS button, as MyMaths will mark you incorrect for rounding errors!

claire21

Ok I'm back with the full question, sorry about yesterday, I thought you maybe just use an equation.

A squared based pyramid has base sides of 230 meters and a height of 147 meters. Using the same material, what would the height be if you have base sides of 290 meters?

egoode

He should work out the volume of the pyramid with the 230m length and width and height of 147m. Once he has the volume of that the volume will be the same for the base with 290m he just needs to change the formula to work out the height instead of volume.

Angry_Bear

claire21 wrote: »

Ok I'm back with the full question, sorry about yesterday, I thought you maybe just use an equation.

A squared based pyramid has base sides of 230 meters and a height of 147 meters. Using the same material, what would the height be if you have base sides of 290 meters?

The volume of a pyramid is length * breadth * height * 1/3

So the first pyramid is 2592100 metres cubed.
As you are using the same materials, the volume of the second pyramid is 2592100 metres cubed.

So now you have to solve:
2592100 = 290*290*height*1/3

So height = 92.46m

[Deleted User]

Why is solving such a simple problem being a maths wizard? Little wonder we're so short of scientists and engineers.