URGENT - Maths Help

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Originally Posted by NavyDiver

This is better if you dont wish to do the maths yourself

Equilateral Triangle Equations Formulas Calculator - Inscribed Circle Radius GeometryInscribed Circle Radius (r)
= 430.12595054627

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I think that for the radius of a circle inside a triangle...I need the radius for a circle on the outside of the triangle.

Use this - Irregular Triangle Calculator

Angles a and c will be 30 degrees (half of the 60 degrees that each corner of the equilateral triangle makes). Side b is your dimension of 1490.

Here's a diagram.

Attachment 126999

Try this link. Move the triangle around in the frame so each side is equal to 14.9 (as per your drawing). It then gives you a radius of 8.6, or diameter of 17.2. Hope that's close enough.

Circumcircle of a Triangle - Math Open Reference


Edit: Beat me to it. Looks like Homestar gets a Gold star!

Quote:

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Originally Posted by weeds

I found this....but it's not making sense to me.

An equilateral triangle of side 6cm is inscribed in a circle. How do I find the radius of the circle? - Quora

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OK......my grade 12 son said the formula is in this link...only problem is I couldn't figure out what root 3 meant...his calculator has it.

Quote:

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Originally Posted by Homestar

Here's a diagram.

Attachment 126999

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Spot on.....

Cheers

Cheers all.....bugger me

I had to engage brain cells I'd not used for many decades... [biggrin]

Pretty happy I haven't killed them all.... yet...

I just engaged Dr Google and as usual it missed[biggrin]

Yes the trigonometry is correct, but as I tell my students if really stuck get some chalk and draw it life size on the ground.
Alternatively draw in a CAD program on computer.

Cheers