Presentation on theme: "Geometry Mr. Nealey 7th Grade"— Presentation transcript:
1 Geometry Mr. Nealey 7th Grade 7.G.5 Triangles and AnglesGeometryMr. Nealey7th Grade
2 Standard/Objectives: Classify triangles by their sides and angles.Find missing angle measures in trianglesDEFINITION: A triangle is a figure formed by three line segments joining three non-collinear points.
3 Names of trianglesTriangles can be classified by the congruency of their sides.Equilateral—3 congruent sidesIsosceles Triangle—2 congruent sidesScalene—no congruent sides
4 Triangles by AnglesTriangles can also be classified by the size of their largest angle. All triangles have at least 2 acute angles, the smallest of the 3.
16 Parts of a triangleEach of the three points joining the sides of a triangle is a vertex.(plural: vertices). A, B and C are vertices.Two sides sharing a common vertext are adjacent sides.The third is the side opposite an angleadjacentSide opposite Aadjacent
17 Right TriangleRed represents the hypotenuse of a right triangle. The sides that form the right angle are the legs.hypotenuselegleg
18 Isosceles TrianglesAn isosceles triangle can have 3 congruent sides in which case it is equilateral. When an isosceles triangle has only two congruent sides, then these two sides are the legs of the isosceles triangle. The third is the base.legbaseleg
19 Identifying the parts of an isosceles triangle Explain why ∆ABC is an isosceles right triangle.In the diagram you are given that C is a right angle. By definition, then ∆ABC is a right triangle. Because AC = 5 ft and BC = 5 ft; AC BC. By definition, ∆ABC is also an isosceles triangle.About 7 ft.5 ft5 ft
20 Identifying the parts of an isosceles triangle Identify the legs and the hypotenuse of ∆ABC. Which side is the base of the triangle?Sides AC and BC are adjacent to the right angle, so they are the legs. Side AB is opposite the right angle, so it is t he hypotenuse. Because AC BC, side AB is also the base.Hypotenuse & BaseAbout 7 ft.5 ft5 ftlegleg
21 Using Angle Measures of Triangles Smiley faces are interior angles and hearts represent the exterior anglesEach vertex has a pair of congruent exterior angles; however it is common to show only one exterior angle at each vertex.