Thread: Construction of tangents

How to construct 2 equal tangents inclined to each other at 60 degrees for a circle of 5 cm .








[/B]Ice Sync
(emo)

I assume you're using just a compass and straightedge. This seems too simple, and maybe flawed, but here goes. Maybe someone with more construction skills can jump in.

Step 1. Construct Circle O with desired radius
Step 2. Locate point P on circle and draw OP and extend past the circle
Step 3. Construct a perpendicular at P and extend (Remember the tangent is perpendicular to the radius at the point of tangency)
Step 4. Construct a segment PR congruent to PO forming equilateral triangle POR (each angle is 60 deg)
Step 5. Construct OR and extend intersecting tangent line at X.
Triangle POX is a 30-60-90 right triangle.
Step 6. Duplicate the 30 deg angle at X and extend to intersect circle at Y, which is the other point of tangency from X

XP = XY and they are 60 deg apart.

Pardon my crude drawing.

Originally Posted by masters

I assume you're using just a compass and straightedge. This seems too simple, and maybe flawed, but here goes. Maybe someone with more construction skills can jump in.

Step 1. Construct Circle O with desired radius
Step 2. Locate point P on circle and draw OP and extend past the circle
Step 3. Construct a perpendicular at P and extend (Remember the tangent is perpendicular to the radius at the point of tangency)
Step 4. Construct a segment PR congruent to PO forming equilateral triangle POR (each angle is 60 deg)
Step 5. Construct OR and extend intersecting tangent line at X.
Triangle POX is a 30-60-90 right triangle.
Step 6. Duplicate the 30 deg angle at X and extend to intersect circle at Y, which is the other point of tangency from X

XP = XY and they are 60 deg apart.

Pardon my crude drawing.

well, good one but too late, but it's a better method actually...