...also the arc BD is the supplement of the arc AB ; and BCD is the supplement of the angle ACB. 11. The sum of the three angles of a triangle is equal to two right angles, or 180°. Hence, if the sum of any two angles of a triangle be subtracted from 180°, the remainder...

...thr gles about the point A, and their sum is plainly two ! angles. 37. The mode of proving that the sum of the three angles of a triangle is equal to two right angles, by cutting a piece of card, is called experimental proof. It is of very little use in mathematics,...

...second, by Prob- VIII ; then will the angle HEF be equal to the third angle of the triangleFor, the sum of the three angles of a triangle is equal to two right angles (Bk- I- Th- xvii) ; and the sum of the three angles on the same side of the line DE fe equal...

...the necessaries of life, or of filling the pocket, it may be difficult to determine. That the s\im of the three angles of a triangle is equal to two right angles, and that the Greeks drove back the Persian invaders, are facts which per se might appear to...

...it make the angles FGH=A, and HGK=B, then KGE will equal the third angle of the triangle, since the sum of the three angles of a triangle is equal to two right angles. At C and D make angles equal to HGK and KGE, and let their sides meet in O; then OCD is the...

...great.y developed. For example, the child can be led to discover, by means of his protractor, that the sum of the three angles of a triangle, is equal to two right-angles, or that the vertical angles formed by the intersection of two lines, are equal. When...

...easy to gather every day, would be to deny a truth which in its way is as plainly shown as that the sum of the three angles of a triangle is equal to two right angles. If now it is announced to us that for the production of another kind of dropsy there is needed...

...side of a triangle is less than the sum and greater than the difference of the other two sides. 2. The sum of the three angles of a triangle is equal to two right angles. 3. The diagonals of a parallelogram bisect each other. 4. An inscribed angle is measured by...

...catch either into other cogged wheels, or into pinions, or into trundles, Ac. Of the Triangle. — The sum of the three angles of a triangle is equal to two right-angles, Ac. Of eimiiar Triangle*. — Two triangles are similar when the ingles of one ar» equal...

...catch either into other cogged wheels, or into pinions, or into trundles, Ac. Of the Triangk. — The sum of the three angles of a triangle is equal to two right-angles, Ac. Of similar Triangles. — Two triangles are similar when the angles of one are equal...