(http://www.palmer934.plus.com/circle.gif)
The green square is perfectly sqaure, the blue circle touchs each side of it. The red section is 14cm x 7cm. Whats the radius of the circle?
28cm.
Well you can measure it as 36!
but measuring wont work as his circle diagram isnt a circle, or its just off of center. :) I can see more green on the left, and green at the top :)
And by my workings out I think its still 28cm.
You just have to scale off the 14 length, and the approx measure is good enough.
Draw a line from the centre of the circle to the corner of the box.
The horizontal distance from the centre point to this point is R-14, call it X
The vertical distance from the centre point to this point is R-7, call it Y
Pythag says Square of Hyp = square of other two sides, so
Rsquared = Xsquared + YSquared = (R-14)squared + (R-7)squared
If you solve that or put R=36 in it works ;) er approximately!
Soz, I shoulda said its not to scale, I wanted to check whether it was a scary math thing or just a case of working out how many red squares fit across the green one.
Yeah you can measure it not to scale as the red box isnt twice length by height.
Its 35 exactly. The people who set these things always have round number solutions! My rusty brain isnt good enough to solve the equation though.
^^^
35 is the correct answer
ahhh doh.
i simply assumed that the red rectangle was meant to divide the quarter arc of the circle in half. which meant as the circle was meant to be bang in the centre of a square that the other side was also perfectly symmetrical itd be the same, and 4 rectangles = length of square side, as in my head the square was the same size as the diameter of the circle...
14x2 = 28 :) lol.