Question : Two medians NA and OB of $\triangle \mathrm{NOP}$ intersect each other at S at right angles. If NA = 15 cm and OB = 15 cm, then what is the length of OA?
Option 1: $5 \sqrt{5} $ cm
Option 2: $7 \sqrt{5}$ cm
Option 3: $6 \sqrt{5}$ cm
Option 4: $3 \sqrt{5}$ cm
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Correct Answer: $5 \sqrt{5} $ cm
Solution : Given, Median NA = 15 cm Median OB = 15 cm Medians intersect at right angles at point S Theorem: The medians of a triangle intersect each other at the centroid, which divides each median in the ratio 2 : 1. As S is the point where the medians intersect, it divides each median in a 2 : 1 ratio, with the longer section towards the midpoint of the side. $\therefore$ the length of OS (longer section of OB) = $\frac{2}{3} ×$15 = 10 cm And, SA (shorter section of NA) = $\frac{1}{3} ×$15 = 5 cm. Since the medians intersect at right angles Applying the Pythagorean theorem, ⇒ OA2 = OS2 + SA2 ⇒ OA2 = (10 cm)2 + (5 cm)2 ⇒ OA2 = 100 cm2 + 25 cm2 ⇒ OA2 = 125 cm2 ⇒ OA = $\sqrt{125}$ cm2 ⇒ OA = 5$\sqrt5$ cm Hence, the correct answer is $5\sqrt5$ cm.
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Question : Two medians JX and KY of $\triangle \mathrm{JKL}$ intersect each other at Z at right angles. If KL = 22 cm and KY = 12 cm, then what is the length of JX?
Option 1: $6 \sqrt{19} \mathrm{~cm}$
Option 2: $3 \sqrt{57} \mathrm{~cm}$
Option 3: $2 \sqrt{57} \mathrm{~cm}$
Option 4: $4 \sqrt{19} \mathrm{~cm}$
Question : The three sides of a triangle are 7 cm, 9 cm, and 8 cm. What is the area of the triangle?
Option 1: $12 \sqrt{3} \;\mathrm{Sq} . \mathrm{cm}$
Option 2: $10\sqrt{3} \;\mathrm{Sq} . \mathrm{cm}$
Option 3: $12 \sqrt{5} \;\mathrm{Sq} . \mathrm{cm}$
Option 4: $2 \sqrt{5} \;\mathrm{Sq} . \mathrm{cm}$
Question : Two medians DM and EN of $\triangle$DEF intersect each other at O at right angles. If EF = 20 cm and EN = 12 cm, then what is the length of DM?
Option 1: 20 cm
Option 2: 12 cm
Option 3: 18 cm
Option 4: 15 cm
Question : In an equilateral triangle, the circumradius is 14 cm. What is the length of the median in this triangle?
Option 1: $14 \sqrt{3} \mathrm{~cm}$
Option 2: $21 \mathrm{~cm}$
Option 3: $18 \sqrt{3} \mathrm{~cm}$
Option 4: $7 \sqrt{3} \mathrm{~cm}$
Question : In an equilateral triangle STU, inradius is $5 \sqrt{3 }\mathrm{~cm}$. What is the length of the side of this equilateral triangle?
Option 1: $20 \sqrt{3} \mathrm{~cm}$
Option 2: $18 \sqrt{3} \mathrm{~cm}$
Option 3: $30 \mathrm{~cm}$
Option 4: $24 \mathrm{~cm}$
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