triangles classification are a and perimeter

CLASSIFICATION OF TRIANGLES

Shadow Teaching Team


Triangles are classified according to its sides or according to its angles.

Classification based on the number of congruent sides:

Scalene triangle - a triangle with no congruent sides

Isosceles triangle - a triangle with at least two congruent sides called the legs

Equilateral triangle a triangle with all sides congruentSPMSMPSPM

Classification based on the kind of interior angles:

Acute a triangle with three acute angles

Obtuse a triangle with one obtuse angle

Equiangular a triangle with three angles congruent

Right angled triangle a triangle with one right angle

SAMBTASPMTRA

Exercises:Classify each triangle as scalene, isosceles or equilateral.QSRPQSPQR

2. Classify each triangle as acute, right, obtuse or equiangularTWUTXVTXUTUVQ35333PSR303025606012035IsoscelesEquilateralScalene rightobtuseEquiangularacuteTXWUV

Classify each triangle according to its given sides or angles.2435832121210105Scalene triangleIsosceles triangleRight angled triangleObtuse triangle

Refer to the diagram. Identify the following triangles.Right triangleEquilateral triangleObtuse triangleAcute triangleScalene triangleIsosceles triangleEquiangular triangleIsosceles-obtuse triangleScalene-right triangleEquilateral-acute triangle60DCBA606030120305

AREA AND PERIMETER OF A TRIANGLE



Shadow Teaching TeamPerimeter is a path that surrounds an area. The word comes from the Greek peri (around) and meter (measure).

The term may be used either for the path or its length - it can be thought of as the distance round a plane figure.

Perimeter of a triangle = a + b + c;where a, b and c are the lengths of the sides of the triangle.


Shadow Teaching TeamThe area of a figure measures the size of the region enclosed by the figure. This is usually expressed in terms of some square unit.

A few examples of the units used are square meters, square centimeters, square inches, or square kilometers.

Area of a triangle =

where, b is the base and h is the height


Shadow Teaching TeamExample # 1:

Find the perimeter and area of the given triangle ABC.

Solution:Perimeter of ABC = 20 m + 12m + 16 m = 48 m

Area of = x b x h

= x 12 x 16 = 96 m2

ABC12 m20 m16 m


Shadow Teaching TeamExample # 2:

Find the base of a triangle of area 80cm2 and height 10cm.

Solution:

Area of = 80 cm2

x b x h = 80 cm2

x b x 10 = 80 cm2

5b = 80 cm2 b = = 16 cm

h = 10 cm b = ?


Shadow Teaching TeamEXERCISES

Find the area of each of the following triangles:

(a)

(b)

18 mm19 cm16 cm10 mmArea = 90 mm2Area = 152 cm2


Shadow Teaching Team ( c)

(d) 9 mm12 mm 6 cm 9 cmArea = 54 mm2Area = 27 cm2


Shadow Teaching Team2. Find the unknown height (h) or base (b) of each of the following triangles:

(a) (b)h8 mmArea = 40mm210 cmbArea = 60cm2Height = 10 mmBase = 12 cm


Shadow Teaching Team(c )

(d) 4 mmArea = 18mm2bArea = 128 cm216 cmBase = 9 mmhHeight = 16 cm


Shadow Teaching Team3. Find the perimeter of an equilateral triangle of side 1.7 cm.

Perimeter = 5.1 cm

4. Find the area of the shaded region. 10 cm6 cm8 cm10 cmArea of the shaded region = 76 cm2


Shadow Teaching TeamA flag is in the shape of an isosceles triangle. Calculatethe length of the lace (in m) required to attach round it, Length of the lace = 3.6 m

(b) the area of the triangle in m2 . Area of the triangle = 0.6 m2

130 cm100 cmlace120 cm


Shadow Teaching Team6. In the figure, AH = 9 cm, AC = 12 cm and BC = 16 cm.Find the area of triangle ABC.Find the perimeter of triangle AHC.

ACHB16 cm12 cm9 cmArea of triangle ABC = 72 cm2Perimeter of triangle AHC = 29 cm


Shadow Teaching Team7. ABCD is a rectangle. The lines AC and BD cross at E. If AB = 4 cm and BC = 6cm, find the area of

Triangle ABC,Triangle ADE.EDACB6 cm4 cmArea of triangle ABC = 12 cm2Area of triangle ADE = 6 cm2


Shadow Teaching Team8. ABCD is a rectangle. Calculate

The area of triangle AEF,The shaded area EBCDF.B 4cm E 3cm A4 cmDC5 cmFArea of triangle AEF = 6 cm2Area of EBCDF = 57 cm2


Shadow Teaching Team9. ABCD is a rectangle in which AB = 4.5 cm and AD = 6 cm. Calculate

The perimeter of the rectangle,The area of triangle BCD.ADCB4.5 cm6 cmPerimeter of the rectangle = 21cmArea of triangle BCD = 13.5 cm2


Shadow Teaching Team10. ABCD is a rectangle and CDE is a straight line. AB = 6 cm, BC = 5 cm and ED = 4 cm. Calculate

The area of triangle ADE,The perimeter of the rectangle ABCD.EA4 cmBDC5 cm6 cmArea of triangle ADE = 10 cm2Perimeter of ABCD = 22 cm


Shadow Teaching Team11. Triangle FDE is cut off from the corner of rectangle ABCDE.Find the perimeter of ABCDF.Find the perimeter of FED.

AFBDCE10 cm3 cm5 cm4 cm5 cmPerimeter of ABCDF = 42 cmPerimeter of FED = 12 cm


Shadow Teaching Team12. ABCD is a rectangle.Calculate the area of triangle ECF.Calculate the shaded area ABEFD.BAFCED2 cm3 cm3 cmArea of triangle ECF = 4.5 cm25 cmArea of triangle ABEFD = 35.5 cm2


Shadow Teaching Team13. A park is in the shape of a triangle ABC. AB = 1 600 m, BC = 2 000 m, CA = 1 200 m and angle CAB = 90.

Calculate the perimeter of the park giving your answers in kilometres.Calculate the area of the park in square meters.CBA1 200 m1 600 m2 000 mPerimeter of the park = 4.8 kmArea of the park = 960 000 m2


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triangles classification are a and perimeter

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