We will discuss here how to find the perimeter of a triangle. We know perimeter of a triangle is the total length (distance) of the boundary of a triangle. Show Perimeter of a triangle is the sum of lengths of its three sides. For example, perimeter of the ∆PQR = PQ + QR + RP ● The perimeter of a triangle ABC = AB + BC + CA = 2 cm + 4 cm + 3 cm, (add the length of each side of the triangle). = 9 cm Perimeter of the triangle = Sum of the sides. ● A triangle has 3 sides The perimeter of the triangle XYZ = 3 cm + 5 cm + 4 cm = 12 cm The perimeter of the triangle = Sum of the lengths of three sides. Let us consider some of the examples on perimeter of a triangle: 1. Find the perimeter of a triangle having sides 3 cm, 8 cm and 6 cm. Solution: Perimeter of a triangle = Sum of all the three sides = AB + BC + AC = 3 cm + 8 cm + 6 cm = 17 cm 2. Find the perimeter of the triangle PQR whose sides are 4 cm, 6 cm and 8 cm. Solution: In the figure PQ = 4 cm, PR = 6 cm and QR = 8 cm The perimeter of the rectangle PQR = 4 cm + 6 cm + 8 cm = 18 cm 3. Find the perimeter of an equilateral triangle whose one side is 5 cm. Solution: A triangle in which all the sides are equal is called an equilateral triangle. Perimeter of the equilateral triangle = 3 × side = 3 × 5 cm = 15 cm Thus, perimeter = 15 cm. 4. Find the perimeter of a triangle whose length of three sides are 8 cm, 11 cm, 13 cm. Solution: To find the perimeter of the triangle, we add all the sides together. Perimeter of a triangle = Sum of all the three sides = 8 cm + 11 cm + 13 cm = 32 cm 5. Find the perimeter of a triangle whose sides are 5 cm, 2 cm and 3 cm. Solution: Perimeter of the triangle is the sum of the lengths of its sides. Perimeter = 5 cm + 2 cm + 3 cm Thus, perimeter = 10 cm. 6. Find the perimeter of each triangle. Solution: (i) Perimeter of ∆XYZ = 5.5 cm + 6 cm + 6 cm = 17.5 cm (ii) Perimeter of ∆ABC = 8 cm + 6 cm + 6 cm = 20 cm (iii) Perimeter of ∆PQR = 4 cm + 3 cm + 5 cm = 12 cm 7. Find the perimeter of the given shapes. Solution: (i) Perimeter = PQ + QR + RS + ST + TU + UV + VP = 2.5 cm + 3 cm + 2 cm + 3 cm + 2.5 cm + 4 cm + 4 cm = 21 cm (ii) Perimeter = PQ + QR + RS + SP = 4 cm + 4 cm + 4 cm + 4 cm = 16 cm (iii) Perimeter = PQ + QR + RS + ST + TP = 7 cm + 6 cm + 4 cm + 3 cm + 5 cm = 25 cm Word Problems on Perimeter of a Triangle: 1. Two sides of a triangle are 3 cm and 4 cm. Find the third side of the triangle if its perimeter is 11 cm. Solution: First side of the triangle = 3 cm Second side of the triangle = 4 cm Perimeter of the triangle = Sum of the lengths of sides i.e. sum of the lengths of the sides = 11 cm 3 cm + 4 cm + length of the third side = 11 cm 7 cm + length of the third side = 11 cm But we know that 7 cm + 4 cm = 11 cm (Note: 11 – 7 = 4) Therefore, length of the third side = 4 cm Questions and Answers on Perimeter of a Triangle: 1. A triangle has a perimeter of 50 cm. If its two sides are of lengths 15 cm and 19 cm, what is the length of the third side? Answer: 16 cm ● Related Concepts ● Units for Measuring Length ● Measuring Instruments ● To Measure the Length of a Line-segment ● Perimeter of a Figure ● Perimeter of a Triangle ● Perimeter of a Rectangle ● Perimeter of a Square ● Unit of Mass or Weight ● Examples on Unit of Mass or Weight ● Units for The Measurement of Capacity ● Examples on Measurement of Capacity ● Measurement of Time ● Read a Watch or a Clock ● Antemeridian (a.m.) or Postmeridian (p.m.) ● What Time it is? ● Time in Hours and Minutes ● 24 Hour Clock ● Units of Time ● Examples Units of Time ● Time Duration ● Calendar ● Reading and Interpreting a Calendar ● Calendar Guides us to Know 4th Grade Math Activities From Perimeter of a Triangle to HOME PAGE Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need. What is the perimeter of a 10cm triangle?Solution: Perimeter of the triangle is the sum of the lengths of its sides. Thus, perimeter = 10 cm.
What is the perimeter of ∆ ABC?Solution. To find the perimeter of \triangle ABC we use the Pythagorean Theorem which tells us that |AB|^2 = |AC|^2 + |BC|^2. Since |AC| = 5 and |BC| = 12 we find that |AB| = \sqrt{169} = 13. The perimeter of \triangle ABC is then 5 + 12 + 13 = 30 units.
Whose two sides are 18 cm and 10 cm and the perimeter is 42 cm?Summary: It is given that in a given triangle two sides are 18cm and 10cm and the perimeter is 42cm. We have found its area equal to 21√11 cm2.
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