...called its vertices (one corner is a vertex). Exterior angle We can also see that it looks as though an exterior angle of a triangle is equal to the sum of the two interior opposite angles. Exercise 3b For each diagram in questions 1 and 2, write down the angle that corresponds to the angle...

...AA a , + a2 = 1 80° angles on a straight line AAAAA .*. al + b+ c= al + a2 AAA /. b+ c = a7 Note: The exterior angle of a triangle is equal to the sum of the two opposite interior angles. 5. Calculate the size of the unknown angles in the following diagrams....

...the sum of the angles p, q and r. (b) Write down the sum of the angles q and x. (c) Hence show that the exterior angle of a triangle is equal to the sum of the interior angles at the other two vertices. 24. The diagram shows two equal squares joined to a...

...properties of parallelograms and a proof that the angle sum of a triangle is 180°; understand a proof that the exterior angle of a triangle is equal to the sum of the interior angles at the other two vertices; l(d) use angle properties of equilateral, isosceles...

...curve must coincide with the axis. [6] So sin * = 0 for 0 < * < 2?r [7] 15.1 Contextual Prove that the exterior angle of a triangle is equal to the sum of the two opposite interior angles: A + B = C. State clearly any axioms used. 2 Without using a calculator...

...also lead to another useful tact about angles in triangles: (2) and (3) => f°+g° = q° + r° ie an exterior angle of a triangle is equal to the sum of the two interior opposite angles. Because this proof does not involve measuring angles in a particular triangle it applies to all possible...

...Fig. 29.9 Since the three angles of a triangle add up to 180°, x + 42 + 68 = 180 x = 180-42-68 = 70 The exterior angle of a triangle is equal to the sum of the opposite interior angles. Hence: y = 42 + 68 = 110 Therefore the angle j is 110°. Exercise 141...

...+ b + с + d + e = 360 d° e 2. Triangles (a) Angle sum of a triangle is 180°. a + b + c= 180 (b) The exterior angle of a triangle is equal to the sum of the opposite interior angles. A С D (c) In an isosceles triangle the base angles are equal. Given...

...of the interior angles of a triangle is equal to 180°. [Abbreviation: < sum of _] X + Y + Z = 180° The exterior angle of a triangle is equal to the sum of the opposite interior angles. [Abbreviation: ext. < of ¿1] C, = A + B ie C, = * + Note: An exterior...

...equilateral isosceles right-angled scalene Interior angles of a triangle add up to 180°. a+h + c= 180° 7 The exterior angle of a triangle is equal to the sum of the interior opposite angles. 8 A polygon with four sides is called a quadrilateral. A quadrilateral...