principle of geometric construction Prepared by: Asst. lecture University Of Warith Al-anbiyaa College of Engineering Bio medical Engineering Department First Class principle of geometric construction Prepared by: Asst. lecture Karrar Al mansoori

(10) Draw an Arc Tangent to a Line and other Arc Given line AB and arc CD Strike arcs R1 (given radius) Draw construction arc parallel to given arc, with center O R1 Draw construction line parallel to given line AB C D From intersection E, draw EO to get tangent point T1, and drop perpendicular to given line to get point of tangency T2 E T1 R1 O A B Draw tangent arc R from T1 to T2 with center E T2

(11) Construct a Pentagon 1- draw the circle at radius R O A 2- divided the radius of the circle at c E R 3- fix the compass at c and open it at radius AC to draw the arc AE B C G 4- fixed the compass at point A with radius AE and draw the arc intersect the circle at point B also draw the other arcs in sequences intersect the circle at points D F G D F

(12) Construct a Hexagon Given distance AB across the corners, draw a circle with AB as the diameter C F D E With A and B as centers and the same radius, draw arcs to intersect the circle at points C, D, E, and F A B Connect the points to complete the hexagon

(13) Construct a Octagon 1- draw the center lines and circle 2- draw the tangent lines to the circle by using t- square and triangle which have 45 degree angle . 45 45

Draw circle tangent to other circle Tangent point R1 C1 R2 C2 R1 + R2 The center of two circles and tangent point lie on the same straight line !!!

(14) Draw a circle tangent to two circles I + Given + C2 + C1 Example

(14) Draw a circle tangent to two circles I Given Two circles and the radius of the third circle = R + + C2 C1

(14) Draw a circle tangent to two circles I Given Two circles and the radius of the third circle = R R + R2 center of the arc R + R1 R2 C R R1 + + C2 C1 Repeat

When circle tangent to other circle Tangent point R1 R2 C1 C2 R2  R1 The center of two circles and tangent point must lie on the same straight line !!!

(15) Draw a circle tangent to two circles II + Given + C2 + C1 Example

(15) Draw a circle tangent to two circles II Given Two circles and the radius of the third circle = R + + C2 C1

(15) Draw a circle tangent to two circles II Given Two circles and the radius of the third circle = R R R2 R1 + + R – R2 C2 C1 R – R1 C Repeat

(16) Draw a circle tangent to two circles III Given Two circles and the radius of the third circle = R R2 R1 + C2 + C1 R + R2 R – R1 C

(17) Draw an approximate ellipse Given Major and minor axes

(17) Draw an approximate ellipse Given Major and minor axes Repeat

How to Keep Your Drawing Clean Do Don’t

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