Факультет: Физика – математика
Кафедра: Математика
Аты жөні: Саткалиева Сымбат
Курс: 3
Топ: М-31
Емтихан тапсырылған күні: 15.05.2020
Пәні: Кәсіби – бағытталған шет тілі
Тақырыбы: Triangle. Area of triangle
Terms
Triangle
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Үшбұрыш
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Треугольник
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Area
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Ауданы
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Площадь
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Angle
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Бұрыш
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Угол
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Perimeter
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Периметр
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Периметр
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Height
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Биіктік
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Высота
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Bisector
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Биссектриса
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Биссектриса
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Median
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Медиана
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Медиана
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Hypotenuse
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Гипотенуза
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Гипотенуза
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Equilateral triangle
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Тең қабырғалы үшбұрыш
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Равносторонний треугольник
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Isosceles triangle
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Теңбүйірлі үшбұрыш
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Равнобедренный треугольник
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Right-angled triangle
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Тік бұрышты үшбұрыш
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Прямоугольный треугольник
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Vertex(of a triangle)
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Төбесі(үшбұрыштың)
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Вершина(треугольника)
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Acute triangle
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Сүйір бұрышты үшбұрыш
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Острый треуголник
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Obtuse angle
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Доғал бұрыш
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Тупой угол
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Side
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Жағы
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Сторона
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What is a Triangle?
In geometry, a triangle is a closed, two-dimensional shape, with three straight sides. A triangle is also a polygon.
Properties of a Triangle
A triangle has three sides, three vertices, and three angles.
The sum of the three interior angles of a triangle is always 180°.
The sum of the length of two sides of a triangle is always greater than the length of the third side.
A triangle with vertices P, Q, and R is denoted as △PQR.
The area of a triangle is equal to half of the product of its base and height.
Different Types of Triangles
To classify triangles according to their angles, we measure each of its interior angles. Triangles can be classified by angles, as:
Triangles by Angles
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Acute
All angles acute
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Right
One right angle
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Obtuse angle
One obtuse angle
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An acute triangle has all interior angles acute (less than 90°), a right triangle has one right angle (equal to 90°) and an obtuse triangle has one obtuse angle (greater than 90°).
To classify the triangles according to their sides, we measure the length of each of its sides. Triangles can be classified by their sides, as:
Triangles by Sides
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Equilateral
All three sides are equal
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Isosceles
Two sides are equal
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Scalene
No sides are equal
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To classify triangles according to both angles and sides, we measure the interior angles and length of the sides of the triangle. Few examples of triangles classified on the basis of both angles and sides are:
Triangles by Sides and Angles
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Acute Equilateral Triangle
All angles measure
All sides are equal.
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Right Isosceles Triangle
One angle
Two sides are equal.
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Obtuse Scalene Triangle
One angle measure
No side is equal.
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Area of triangle
There are several ways to find the area of a triangle.
Knowing base and height
The area of a triangle is equal to half of the product of its base and height:
Example: What is the area of this triangle?
(Note: 12 is the height, not the length of the left-hand side)
Knowing three sides
S tep 1: Calculate “S” (half of the triangles perimeter):
Step 2: Then calculate the Area:
Example: What is the area of a triangle where every side is 5 long?
Step 1: Calculate “S” (half of the triangles perimeter):
Step 2: Then calculate the Area:
Knowing Two Sides and the Included Angle
When we know two sides and the included angle (SAS), there is another formula (in fact three equivalent formulas) we can use.
Depending on which sides and angles we know, the formula can be written in three ways:
They are really the same formula, just with the sides and angle changed.
E xample: Find How Much Land
Farmer Jones owns a triangular piece of land.
The length of the fence AB is 150 m. The length of the fence BC is 231 m.
The angle between fence AB and fence BC is 123º.
How much land does Farmer Jones own?
First of all we must decide which lengths and angles we know:
So we use:
Put in the values we know
Do some calculator work:
Farmer Jones has 14.530 m2 of land.
The list of used literature
https://www.mathsisfun.com/algebra/trig-area-triangle-without-right-angle.html
https://en.wikipedia.org/wiki/Triangle
James R. Newman; The world of mathematics, Vol.1
Kevin McCrimmon (2004) A Taste of Jordan Algebras, pp 49,
Laurie Buchanan; Jim Fensom. Mathematics standard level. Oxford, 2012
https://www.dkfindout.com/us/math/geometry/types-triangle
https://www.mathsisfun.com/triangle.html
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