Then the q coordinate is (5-rcost, -5-rsint). Note: The symmetrical point coordinates of point (x0, y0) relative to point (x 1, y 1) are (
X2, y2), x 1 = (x0+x2)/2, y 1 = (y0+y2)/2, so it is easy to know that x2 = 2x1-x0.y2 = 2y1-y0.
The coordinate of point s is (-5-rsint, 5+rcost). Note: If the point (x, y) rotates 90 relative to the origin, the straight line formed by the new point (x 1, y 1) is perpendicular to the straight line formed by the origin and (x, y). The product of slopes is-1. It is easy to calculate whether the new point is (-y, x) or (y, -x). It is (-y, x) because it rotates counterclockwise.
SQ？ =(- 10-rsint+rcost)？ +( 10+rcost+rsint)？ = 100+20rsint-20rcost+r？ -2r？ costs int+ 100+20r cost+20r Sint+r？ +2r？ sintcost=200+2r？ +40rsint
SQ？ The maximum value is obtained when sint= 1, that is, 200+2r? +40r=2(r+ 10)？
SQ？ When sint=- 1, the minimum value is obtained, that is, 200+2r? -40r=2(r- 10)？
The maximum value of |SQ| is the root number 2 of (r+ 10).
The minimum value of |SQ| is |r- 10| root number 2 Note: the root number here depends on the relationship between r and 10.
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