Saved Bookmarks
| 1. |
An umbrella is made by stitching 8 triangular pieces of cloth of two different colours, each piece measures 60cm, 60cm and 20cm. How much cloth of each colour is required for the umbrella?(a) \(50\sqrt{35} cm^2\)(b) \(25\sqrt{65} cm^2\)(c) \(50\sqrt{45} cm^2\)(d) \(25\sqrt{55} cm^2\)I have been asked this question in semester exam.Question is from Application of Heron’s Formula in finding Areas of Quadrilaterals in chapter Heron’s Formula of Mathematics – Class 9 |
|
Answer» CORRECT option is (a) \(50\sqrt{35} cm^2\) The explanation: s = \(\frac{a+b+c}{2}=\frac{60+60+20}{2} = \frac{140}{2}\) = 70 According to heron’s FORMULA, AREA of the triangle = \(\sqrt{s*(s-a)*(s-b)*(s-c)}\) = \(\sqrt{70*(70-60)*(70-60)*(70-20)}\) = \(\sqrt{70*10*10*50}\) = 100\(\sqrt{35} cm^2\) This area is the combined area of both colours. Hence, area of each colour = \(\frac{100\sqrt{35}}{2}\) = \(50\sqrt{35} cm^2\). |
|