CBSE Class 10 Sample Paper for 2022 Boards - Maths Basic [MCQ]
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CBSE Class 10 Sample Paper for 2022 Boards - Maths Basic [MCQ]
Last updated at April 16, 2024 by Teachoo
This question is inspired from Question 13 - Sample Papers 2020 - Maths Standard - [Also, check proof of the formula]
Question 33 The perimeters of two similar triangles are 26 cm and 39 cm. The ratio of their areas will be (a) 2 : 3 (b) 6 : 9 (c) 4 : 6 (d) 4 : 9 Let ΔABC and ΔPQR be two similar triangles Now, Ratio of perimeter of two similar triangles is equal to ratio of their corresponding sides ∴ (𝑷𝒆𝒓𝒊𝒎𝒆𝒕𝒆𝒓 Δ 𝑨𝑩𝑪)/(𝑷𝒆𝒓𝒊𝒎𝒆𝒕𝒆𝒓 Δ 𝑷𝑸𝑹)=𝑨𝑩/𝑷𝑸 26/39=𝐴𝐵/𝑃𝑄 2/3=𝐴𝐵/𝑃𝑄 𝑨𝑩/𝑷𝑸=𝟐/𝟑 We know that Ratio of area of similar triangles is equal to square of ratio of its corresponding sides Therefore, (𝐴𝑟𝑒𝑎 𝑜𝑓" " ∆𝐴𝐵𝐶)/(𝐴𝑟𝑒𝑎 𝑜𝑓" " ∆𝑃𝑄𝑅)=(𝐴𝐵/𝑃𝑄)^2 Putting values (𝐴𝑟𝑒𝑎 𝑜𝑓" " ∆𝐴𝐵𝐶)/(𝐴𝑟𝑒𝑎 𝑜𝑓" " ∆𝑃𝑄𝑅)=(2/3)^2 (𝑨𝒓𝒆𝒂 𝒐𝒇" " ∆𝑨𝑩𝑪)/(𝑨𝒓𝒆𝒂 𝒐𝒇" " ∆𝑷𝑸𝑹)=𝟒/𝟗 Hence, the required ratio is 4 : 9 So, the correct answer is (d)
