[問題]GWD 18-21

[peche]

21 In the figure shown, the circle has center O and radius 50, and point P has coordinates (50,0). If point Q (not shown) is on the circle, what is the length of line segment PQ ?
(1) The x-coordinate of point Q is – 30.
(2) The y-coordinate of point Q is – 40.

--> i got D, 因為半徑已知
不懂為何答案是A

--> 请問on the circle 是在圓上的意思嘛?

謝謝~麻煩大家幫忙解答~

[reohuang]

if x=-30, then it might be a (-30, 40) or b (-30, -40), and both points to the point P is the same
(even do not need to calculate, one souletion only)

if y=-40, then it might be b (-30, -40) or c (30, -40), and those two points have different distances to the point P
(two possible solutions)

for your reference

[peche]

阿~ 了解~
thanks alot!

[vigor]

ok...原來也要考慮二三象限的情形
有點小tricky
感謝囉

[Msmistake]

請問一下這題的p 點有在circle上嗎?
如果沒有該怎麼算阿?