The difference between the sides at right angles in a right-angled
triangle is 14 cm. The area of the triangle is 120 cm?. Calculate the
perimeter of the triangle.
Answers
Answer:
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Question :
The difference between the sides at the right angles in a right-angled triangle is 14 cm. The area of triangle is 120 cm^2. Then calculate the perimeter of the triangle.
Answer :
Perimeter = 60 cm
Note :
- The sides at the right angle in a right-angled triangle are its base and perpendicular.
- The side which lies opposite of the right angle in a right-angled triangle is its hypotenuse.
- The area of any triangle is given as;
Area = (1/2)•(Base)(Height)
OR
Area = (1/2)•(Base)(Perpendicular)
- Pythagoras theorem : In a right-angled triangle, the square of the hypotenuse is equal to the sum of square of the other two perpendicular sides.
- h^2 = b^2 + p^2
- Perimeter of a polygon is given by the sum of the lengths of its all sides.
Solution :
It is given that,
The difference between the sides at the right angles in a right-angled triangle is 14 cm.
Thus,
Let the base of the given right-angled triangle be x cm.
And,
Let the perpendicular of the given right-angle triangle be (x+14) cm.
Also,
It is given that;
The area of triangle is 120 cm^2
=> Area = 120
=> (1/2)•(Base)(Perpendicular) = 120
=> (Base)(Perpendicular) = 120•2
=> (Base)(Perpendicular) = 240
=> x(x+14) = 240
=> x^2 + 14x = 240
=> x^2 + 14x - 240 = 0
=> x^2 + 24x - 10x - 240 = 0
=> x(x + 24) - 10(x + 24) = 0
=> (x + 24)(x - 10) = 0
=> x = -24 , 10
Since,
Length can't be negative, thus x = -24
is rejected value.
Hence,
The appropriate value is x = 10.
Thus,
Base of the triangle = x cm = 10 cm
Perpendicular of the triangle
= (x+14) cm
= (10+14) cm
= 24 cm
Now,
Applying Pythagoras theorem in the given triangle,
We get;
=> h^2 = b^2 + p^2
=> h^2 = (10)^2 + (24)^2
=> h^2 = 100 + 576
=> h^2 = 676
=> h = √676
=> h = 26
Hence,
Hypotenuse of the triangle = 26 cm.
Here,
The perimeter of the triangle will be given by;
=> Perimeter = b + p + h
=> Perimeter = (10 + 24 + 26) cm
=> Perimeter = 60 cm.
Hence;
The perimeter of the given right-angled triangle is 60cm.