TRIANGLES AND QUADRILATERALS |
Objectives
Name and classify triangles. Name and classify quadrilaterals. Find the measures of angles in these figures. |
Vocabulary
Quadrilateral, parallelogram, rhombus, trapezoid, rectangle, square, equilateral triangle, isosceles triangle, scalene triangle, right triangle, acute triangle, obtuse triangle
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Triangle is a popular shape to use in construction. Triangles are rigid. There are two ways to classify triangles by their side and by their angles. |
Triangles have three sides, three vertices, and three angles. The parts of the triangles are the height, or altitude, of a triangle is a line segment that starts at any vertex and is perpendicular to the opposite side of the triangle called the base. To name a triangle, use the vertices. Write ABC Say: Triangle ABC |
Equilateral triangle
all the
sides have the same length.
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Isosceles triangle two sides have the same length. | Scalene triangle no two sides have the same length. |
Right triangle one right angle. | Acute triangle all angles are acute. | Obtuse triangle
one obtuse
angle.
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The sum of the measures of the angles of any triangle is 180º. 50º + 110º + 20º = 180º
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---------------------Try It Out--------------------------- Name each triangle according to the lengths of its sides. |
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3. |
Name each triangle according to the measure of its angles. |
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5.
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Find the measure of the third angle in the triangle. 6.
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Quadrilaterals |
Quadrilaterals is a closed 2-dimensional figure with four sides that are line segments. some quadrilaterals have special traits, so they have special names. |
Parallelogram
has two pairs of parallel sides and two pairs of congruent sides. In
other words opposite sides the same length and parallel.
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Rectangle
is a parallelogram with four right angles.
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Square
is a parallelogram, rectangle, rhombus. A square has four right
angles and four congruent sides.
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Rhombus
is a parallelogram with four congruent sides.
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Trapezoid has exactly one pair of parallel sides. |
The sum of the measures of the angles of any quadrilateral is 360º. 87º + 76º + 98º + 99º = 360º
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Classify each quadrilateral as many ways as you can. |
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Click here to take the quiz on triangles and quadrilaterals. Remember to ask Ms.Painter for the password. |
Isosceles triangle | Equilateral triangle | Scalene triangle |
Acute triangle | Obtuse triangle | 66 + 24 + x =
180
89 + x = 180 -89 -89 x = 91º |
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1) Parallelogram
Quadrilaterals |
2) Quadrilateral
Parallelogram Rectangle |
3) Quadrilateral
Parallelogram Rhombus Rectangle Square |