Question:
Top surface of a raised platform is in the shape of a regular octagon as shown in the figure. Find the area of the octagonal surface.
Top surface of a raised platform is in the shape of a regular octagon as shown in the figure. Find the area of the octagonal surface.
Updated On: Mar 12, 2025
Hide Solution
Verified By Collegedunia
Solution and Explanation
Side of regular octagon = 5 cm
Area of trapezium ABCH = Area of trapezium DEFG
Area of trapezium ABCH = \(\frac{1}{2} × \)(AB + CH) \(×\) AI
\(= \frac{1}{2} ×\) (5 m + 11 m) \(×\) 4 m
\(= \frac{1}{2} ×\) 16 m \(×\) 4 m
= 32 m²
Area of rectangle HGDC \(= 11 × 5 = 55\) m2
Area of octagon = Area of trapezium ABCH + Area of trapezium DEFG + Area of rectangle HGDC
= 32 m2 + 32 m2 + 55 m2 = 119 m2
Was this answer helpful?
2
0
Top Questions on Area of a Polygon
- The area of a trapezium is 34 cm2 and the length of one of the parallel sides is 10 cm and its height is 4 cm. Find the length of the other parallel side.
- CBSE Class VIII
- Mathematics
- Area of a Polygon
- The diagonals of a rhombus are 7.5 cm and 12 cm. Find its area.
- CBSE Class VIII
- Mathematics
- Area of a Polygon
- Diagram of the adjacent picture frame has outer dimensions = 24 cm x 28 cm and inner dimensions 16 cm x 20 cm. Find the area of each section of the frame, if the width of each section is same.
- CBSE Class VIII
- Mathematics
- Area of a Polygon
- There is a pentagonal shaped park as shown in the figure.
For finding its area Jyoti and Kavita divided it in two different ways. Find the area of this park using both ways. Can you suggest some other way of finding its area?- CBSE Class VIII
- Mathematics
- Area of a Polygon
- Mohan wants to buy a trapezium shaped field. Its side along the river is parallel to and twice the side along the road. It the area of this field is 10500 m2 and the perpendicular distance between the two parallel sides is 100 m, find the length of the side along the river.
- CBSE Class VIII
- Mathematics
- Area of a Polygon
View More Questions
Questions Asked in CBSE Class VIII exam
- Match items in column A with those in column B.
A B (i) Kharif crops (a) Food for cattle (ii) Rabi crops (b) Urea and super phosphate (iii) Chemical fertilizers (c) Animal excreta, cow dung urine and plant waste (iv) Organic manure (d) Wheat, gram, pea (e) Paddy and maize - CBSE Class VIII
- Harvesting
- Subtract 4p2q – 3pq + 5pq2 – 8p + 7q – 10 from 18 – 3p – 11q + 5pq – 2pq2 + 5p2q
- CBSE Class VIII
- Addition and Subtraction of Algebraic Expressions
- Simplify.
(i) (x2– 5) (x + 5) + 25
(ii) (a2+ 5) (b3+ 3) + 5
(iii) (t + s2) (t2 – s)
(iv) (a + b) (c – d) + (a – b) (c + d) + 2 (ac + bd)
(v) (x + y) (2x + y) + (x + 2y) (x – y)
(vi) (x + y) (x2– xy + y2)
(vii) (1.5x – 4y) (1.5x + 4y + 3) – 4.5x + 12y
(viii) (a + b + c) (a + b – c)- CBSE Class VIII
- Multiplying a Polynomial by a Polynomial
- Factorise
- \(x^ 2 + xy + 8x + 8y\)
- \(15xy - 6x + 5y - 2 \)
- \(ax + bx - ay - by\)
- \(15pq + 15 + 9q + 25p\)
- \(z - 7 + 7xy - xyz\)
- CBSE Class VIII
- What is Factorisation?
- Give reasons.
- Water is not used to control fires involving electrical equipment.
- LPG is a better domestic fuel than wood.
- Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
- CBSE Class VIII
- What is a Fuel?
View More Questions