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Chris is swimming in a lake, 50m from the shore.
Her family are 100m along the shore.
She'd like to get back to her family as quickly as possible. If she can swim at 3 m/sec and run at 7m/sec, how far along the shore should she land in order to get back as quickly as possible?
A circle touches the lines OA, OB and AB where OA and OB are perpendicular. Show that the diameter of the circle is equal to the perimeter of the triangle
A 1 metre cube has one face on the ground and one face against a wall. A 4 metre ladder leans against the wall and just touches the cube. How high is the top of the ladder above the ground?
The area of a regular pentagon looks about twice as a big as the pentangle star drawn within it. Is it?