...180°. Hence the sum of the three angles of triangle ABC is also 180°. Exterior Angle Theorem. An exterior angle of a triangle is equal to the sum of the two non-adjacent interior angles of the triangle. Proof: This follows easily from the Angle Sum Theorem. Obviously, no two sides of...

...parallelograms and a proof that the angle sum of a triangle is 180 degrees; understand a proof that the exterior angle of a triangle is equal to the sum of the interior angles at the other two vertices 2(d) Use angle properties of equilateral, isosceles and...

...+ 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...

...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...

...corresponding angles • Angles on a straight line add up to 180°. Angles in a triangle add up to 180°. The exterior angle of a triangle is equal to the sum of the interior angles at the other two vertices. Vertically opposite angles are equal. Base angles of...

...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...

...understand a proof that: - the sum of the angles of a triangle is 180* and of a quadrilateral is 360° - the exterior angle of a triangle is equal to the sum of the two interior opposite anglesChapter 1 1 Lines and Angles Parallel and perpendicular lines page...

...corresponding angles. c Understand a proof that the angle sum of a triangle is 180° and a proof that the exterior angle of a triangle is equal to the sum of the interior angles at the other two vertices; explain why the angle sum of any quadrilateral is 360°....

...structured way the proof that the angle sum of a triangle is 180°. Question 6 deals with the proof that the exterior angle of a triangle is equal to the sum of the opposite interior angles. This is not structured but it is essentially the same proof and should...