Mathematics
Lengths of sides of triangle are given below. Determine which of them are right triangles. In case of a right triangle, write the length of its hypotenuse:
(i) 3 cm, 8 cm, 6 cm
(ii) 13 cm, 12 cm, 5 cm
(iii) 1.4 cm, 4.8 cm, 5 cm
Answer
Choose the greatest length. Check whether the square of greatest length is equal to the sum of squares of other two lengths.
(i) Here greatest length is 8 cm and other lengths are 3 cm, 6 cm.
Note that 82 = 64 and 32 + 62 = 9 + 36 = 45.
Note that, 64 ≠ 45.
Hence, the triangle with given lengths of sides is not a right triangle.
(ii) Here greatest length is 13 cm and other lengths are 5 cm, 12 cm.
Note that 132 = 169 and 52 + 122 = 25 + 144 = 169.
Thus, 132 = 52 + 122.
Hence, the triangle with given lengths of sides is a right triangle and length of hypotenuse is 13 cm.
(iii) Here greatest length is 5 cm and other lengths are 1.4 cm, 4.8 cm.
Note that 52 = 25 and (4.8)2 + (1.4)2 = 23.04 + 1.96 = 25.
Thus, 52 = (4.8)2 + (1.4)2.
Hence, the triangle with given lengths of sides is a right triangle and length of hypotenuse is 5 cm.
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