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MATH / In the diagram, two circles, each with center D, have radii of 1 and 2. The total area of the shaded region is (5)/(12) of the area of the larger circle. How many degrees are in th…

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problem

In the diagram, two circles, each with center DD, have radii of 11 and 22. The total area of the shaded region is 512\frac5{12} of the area of the larger circle. How many degrees are in the measure of (the smaller) ∠ADC\angle ADC? [asy] size(4cm); defaultpen(linewidth(0.75)); real adc = 100; pair d = (0, 0); pair a = 2 * dir(100); pair c = (2, 0); path inner = arc(d, a/2, c/2, CW); path outer = arc(d, c, a, CCW); guide region1 = (a--a/2)..inner..(c/2--c)..outer..cycle; guide region2 = arc(d, a/2, c/2, CCW)..(c/2--d--a/2)..cycle; fill(region1, gray(0.75)); fill(region2, gray(0.75)); draw(unitcircle); draw(scale(2) * unitcircle); draw(a--d--c); label("AA", a, N); label("CC", c, E); label("DD", d, NE); [/asy]
Plain-text mathematical notation (without MathML)
In the diagram, two circles, each with center D, have radii of 1 and 2. The total area of the shaded region is (5)/(12) of the area of the larger circle. How many degrees are in the measure of (the smaller) ∠ADC?
[asy]
size(4cm);
defaultpen(linewidth(0.75));
real adc = 100;
pair d = (0, 0); pair a = 2 * dir(100); pair c = (2, 0);
path inner = arc(d, a/2, c/2, CW);

path outer = arc(d, c, a, CCW);
guide region1 = (a--a/2)..inner..(c/2--c)..outer..cycle;
guide region2 = arc(d, a/2, c/2, CCW)..(c/2--d--a/2)..cycle;
fill(region1, gray(0.75));
fill(region2, gray(0.75));
draw(unitcircle); draw(scale(2) * unitcircle);
draw(a--d--c);
label("A", a, N); label("C", c, E); label("D", d, NE);
[/asy]
Original LaTeX notation
In the diagram, two circles, each with center $D$, have radii of $1$ and $2$. The total area of the shaded region is $\frac5{12}$ of the area of the larger circle. How many degrees are in the measure of (the smaller) $\angle ADC$?
[asy]
size(4cm);
defaultpen(linewidth(0.75));
real adc = 100;
pair d = (0, 0); pair a = 2 * dir(100); pair c = (2, 0);
path inner = arc(d, a/2, c/2, CW);

path outer = arc(d, c, a, CCW);
guide region1 = (a--a/2)..inner..(c/2--c)..outer..cycle;
guide region2 = arc(d, a/2, c/2, CCW)..(c/2--d--a/2)..cycle;
fill(region1, gray(0.75));
fill(region2, gray(0.75));
draw(unitcircle); draw(scale(2) * unitcircle);
draw(a--d--c);
label("$A$", a, N); label("$C$", c, E); label("$D$", d, NE);
[/asy]

level

Level 4

type

Geometry

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