Question

Eason

求解

EM
6. 如右圖,梯形ABCD中,若∠C=∠D=90°,AD=9, BD=27,且
AB的中垂線過C點交4B於P點,則CD=18
O
B
or

Answer 1

00

中垂線上任一點到兩點等長→AC=BC
設CD=x
(△ACD)81+x^2=AC^2
(△BCD)729-x^2=BC^2
(AC^2)=(BC^2)→81+x^2=729-x^2,2•x^2=648
x^2=324→x=18