A point S is taken on the side QR of triangle PQR such that RS = 2SQ. It is known that Angle PQR = 45^{o} and Angle SPQ = 15^{o}
Determine Angle PRQ.
Start with a line. Erect a perpendicular. Using a point on each line, bisect the angle, making the 45degree angle at Q.
Using arbitrary point C on the perpendicular as a center and twice its distance to Q as a radius, construct a circle, intersecting the original line at P. Bisect CPQ. The bisector cuts the bisector of the 90degree angle at S. Measure off twice QS from S to R.
Geometer's Sketchpad now shows angle PRQ to be 75 degrees.

Posted by Charlie
on 20071029 11:47:30 