Elementary plane geometry : inductive and deductive / by Alfred Baker (1903)
Baker, Alfred, 1848-1942 · Toronto : Gage · leaf 93
Angles in a Circle. 89 Since a quadrilateral can be divided into two tri-angles by joining its opposite angles, the snm of allthe angles of any quadrilateral is four right anglesiHence if the sum of a pair of opposite angles be tworight angles, the sum of the other pair is two rightangles also. … 4. Describe a circle, and inthe semicircle construct a num-ber of angles as indicated in thefigure. Adjust the protractor tothe angles ADB, AEB, ....What is the magnitude of theseangles ? The magnitude of the anglein a semicircle may be j^roved thus : The straightangle ACB at the centre is (Ch.…
Geometry, Plane
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