Mathematics and Society - OS X Lion Server

Over 2,000 years ago a Greek scientist, Eratosthenes (er-a-tas'-the- nez), measuredthe circumference of the earth. His method involved: 1) measuring the angle betweenthe Sun's rays and the zenith and 2) using parallel lines to find the circumference ofa circle.(1. To find the angle between the Sun's rays and the zenith:a. Mount a drinking straw in clay andplace it straight up on a piece ofcardboard. (The straw makes a 90°angle with the board.)b. Place this straw On a level surfacein sunlight and measure the lengthof the shadow cast by the straw.c. Find the length of the straw andmake a scale drawing of the triangle.The drawing could be done on graphpaper.5~ADOW/d. Use your scale drawing to find theangle between the Sun's rays and thezenith.e. Does the time of day affectthe angle between the Sun'sis the shadow the shortest?what way?the size of the angle? Measure the shadow and findrays and zenith at one hour intervals. At what hourAs the shadow increases, does the angle change? In2. To find the circumference of a circle using parallel lines:TCEt0TE:R10