# Triangle Area

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In this section, we will study the Area of Triangles, but triangles of several types of triangles such as acute triangle, right triangle, isosceles triangle, equilateral triangle and obtuse triangle .

**Some solved examples**

1) Find the height of an acute triangle whose base is 20 cm and area is 150 cm

^{2}.

**Solution :**

Area = ½ base x height

150 = ½ x 20 x height

150 = 10 x height

∴ height = 150 / 10 = 15 cm.

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2) In a right triangle , if base is 20 m and height is 5 m, find the area of triangle.

**Solution :**

Area = ½ x base x height

A = ½ x 20 x 5

A= 100 / 2

A = 50 m

^{2}

Area = ½ x base x height

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3) Find the area of isosceles right triangle , if one of the equal side is 20 in long.

**Solution :**

In right triangle any one of the two sides which are at right angle can be taken as the base and other side as height.

Area = ½ x 20 x 20

Area = 200 cm

^{2}

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4) Find the area of equilateral triangle with sides 8 cm.

**Solution :**

Area of equilateral triangle = ( √ 3 a

^{2}) / 4

Area = ( √ 3 x 8

^{2}) / 4

Area = ( √ 3 x 64 ) / 4

Triangle Area = 16 √ 3 cm

^{2}

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5) ABCD is a rectangle with dimensions 32 m by 18 m. ADE is a triangle such that EF ⊥ AD and EF = 14 cm. Calculate the area of the shaded region.

**Solution :**

Area of rectangle ABCD = l x w

A = 32 x 18 = 576 m

^{2}

Area of Triangle ADE = ½ x base x height

A = ½ x 18 x 14

A= 126 m

^{2}

Area of shaded region = Area of rectangle ABCD – Area of triangle ADE

A = 576 – 126 = 450 m

^{2}

∴ Area of shaded region = 450 m

^{2}

**Mensuration : Area and Perimeter**

• Perimeter and Area of Irregular Shape

• Area and Perimeter of the Rectangle

• Area of Square (perimeter of square)

• Perimeter of Parallelogram(Area of Parallelogram)

• Area of Rhombus(Perimeter of rhombus)

• Area of Trapezoid (Trapezium)

• Triangle Area (Perimeter of triangle)

• Herons Formula

• Perimeter and Area of Irregular Shape

• Area and Perimeter of the Rectangle

• Area of Square (perimeter of square)

• Perimeter of Parallelogram(Area of Parallelogram)

• Area of Rhombus(Perimeter of rhombus)

• Area of Trapezoid (Trapezium)

• Triangle Area (Perimeter of triangle)

• Herons Formula

7th grade math

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