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The hypotenuse of a right triangle is 25 cm. The difference between the lengths of the other two sides of the triangle is 5 cm. Find the lengths of these sides. |
Answer» Given: The hypotenuse of a right triangle is 25 cm. The difference between the lengths of the other two sides of the triangle is 5 cm. To find: the lengths of these sides. Solution: We know(Hypotenuse)2 = (perpendicular)2 + (base)2 ..... (1) Given, hypotenuse of a right triangle is 25 cm. The difference between the lengths of the other two sides of the triangle is 5 cm Let the base be ‘b’. ⇒ Perpendicular = b – 5Put the known values in (1), ⇒ 252 = b2 + (b – 5)2 Apply the formula (x – y)2 = x2 + y2 - 2xy in (b – 5)2. Here x = b and y = 5 ⇒ 625 = b2 + b2 + 25 – 10b ⇒ 625 = 2b2+ 25 – 10b ⇒ 2b2+ 25 – 10b = 625 ⇒ 2b2+ 25 – 10b - 625 = 0 ⇒ 2b2– 10b - 600 = 0 Take out 2 common of the above equation. ⇒ b2 – 5b – 300 = 0 Factorise the above quadratic equation by splitting the middle term. ⇒ b2 – 20b + 15b – 300 = 0 ⇒ b(b – 20) + 15(b – 20) = 0 ⇒ (b - 20 ) ( b + 15 ) = 0 ⇒ (b - 20 ) = 0 and ( b + 15 ) = 0 ⇒ b = 20 and b=-15 Since the length of any side cannot be negative, We will ignore -15. ⇒ b = 20 Perpendicular = 20 – 5 = 15 Hence,Sides are 15 and 20 |
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