Current location - Training Enrollment Network - Mathematics courses - 20 12 Mathematics for Senior High School Entrance Examination in Guiyang
20 12 Mathematics for Senior High School Entrance Examination in Guiyang
Hint, there is something wrong with the graphic letters in the supplementary question, and the positions of A and D should be reversed.

(1) link OE

Because CD is tangent to o and e,

So OE vertical CD

And because AB= 10.

So OE=5.

(2) If A is AF, the vertical CD is in F,

Because the quadrilateral ABCD is a parallelogram, OE is perpendicular to CD.

So OA=OE=EF=AF=5,

Because ∠ ABC = 60

So ADC = 60.

In the RT triangle, ∠ ADC = 60, ∠ AFD = 90,

So DF=5/3 times√ 3.

That is, DE=5+5/3 times √3.

S shadow = S trapezoid AOED-S fan OAE=25/4+5/6 times √3.