A geometry problem by Majed Musleh

Geometry Level pending

In the above image if r = 20 r=20 Find the area of L + G L+G

100(Pi-2) 10(Pi-2) 20(Pi-2) 50(Pi-2)

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Majed Musleh
Mar 6, 2016

First i will write the equations of the three circles A x 2 + y 2 = 400 B ( x 10 ) 2 + y 2 = 100 C x 2 + ( y 10 ) 2 = 100 A- \ x^{2}+y^{2}=400 \\B- \ (x-10)^{2}+y^2=100 \\ C- x^2+(y-10)^2=100 Now the area L = G L=G how? G = t h e a r e a o f q u a r t e r A B C t h e a r e a o f t h e s e m i c i r c l e B C t h e s e m i c i r c l e A C + L G=\ the \ area \ of \ quarter \ ABC -\ the\ area \ of \ the\ semi \ circle \ BC \ - \ the\ semi\ circle \ AC+L we add L L because we substract it twice when we substract the two semicircles G = π 2 0 2 4 π 1 0 2 2 π 1 0 2 2 + L G=\pi \frac{20^{2}}{4}-\pi \frac{10^{2}}{2}-\pi \frac{10^{2}}{2}+L do the calculation ... = > G = L => G=L now we need to find the points of intersection from eq. B B and eq. C C x 2 20 x + 100 + y 2 = x 2 + y 2 20 y + 100 x^{2}-20x+100+y^{2}=x^{2}+y^{2}-20y+100 => x = y \boxed{x=y} =>substitute in eq. B B we get y = 0 = > x = 0 o r y = 10 = > x = 10 y=0 \ => \ x=0 \ or \boxed{y=10 \ => x=10} the points of intersection leads us to drow the square with side length 10 10 as shown in the photo now the area of G = t h e a r e a o f q u a r t e r A B C t h e a r e a o f t h e s q u a r e 2 t h e a r e a o f t h e q u a r t e r o f c i r c l e w i t h r = 10 G=\ the \ area \ of \ quarter \ ABC -\ the\ area \ of \ the\ square \\ -2 \ the\ area \ of \ the \ quarter \ of \ circle \ with \ r=10 G = π 2 0 2 4 1 0 2 2 π 1 0 2 4 G=\pi \frac{20^{2}}{4}-10^{2}-2\pi\frac{10^{2}}{4} = 50 π 100 50\pi-100 = 50 ( π 2 ) 50(\pi-2) Finally L + G = 2 50 ( π 2 ) = 100 ( π 2 ) L+G=2*50(\pi-2)=\boxed{100(\pi-2)}

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...