Triangles, Congruence and Angles Slideshow 37, Mathematics Mr Richard Sasaki Room 307 Objectives Learn some triangle and angle notation Learn some triangle and angle notation Look at different types of angle Look at different types of angle Understand the meaning of congruence and notation for congruence Understand the meaning of congruence and notation for congruence Triangle Notation Look at the triangle below. What names could it have? All combinations are valid but its best to name things in alphabetical order when possible. What should we name this square? Note: Names must contain adjacent vertices. Note: Adjacent means next to or aside. Angle Notation What do we call the angle below? We call this angle. Lets try to be as clear as possible! Types of Angle Acute Obtuse Reflex A right-angle A straight-angle A full rotation Answers - Easy Answers - Hard Draw the angle on and label it. Congruence What is congruence? Congruence occurs when two shapes are congruent. This means that they are the same and same. size shape Note: Same shape implies that corresponding angles are the same size and edges are the same length. Where is the line of symmetry on this isosceles triangle? It splits this triangle into two right-angled triangles. congruent Note: Congruent shapes can be transposed, rotated or flipped. Congruence Look at the diagram below. Which triangles (by name) are congruent to which? The symbol for congruence is or. So, we can say Answers The lines on the parallelogram. No they cant. Triangle and quadrilateral. quadrilaterals line 2 trapeziums sizeshape edges angles No. Stars and the rhombus have edges the same length and are not regular. (pentagons) (0) (irregular pentagons)