SarkariPYQ

SSC CGL 2022 PYQ — Question 93

SSC CGL Tier II - Quant - 29 Jan 2022 • Quantitative Aptitude • Q93

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The base of the right pyramid is an equilateral triangle, each side of which is 20 cm. Each slant edge is 30 cm. The vertical height (in cm) of the pyramid is:

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Correct answer: D

Explanation

  The correct answer is option 4 i.e.  10√233√\frac{23}{3} 

PQ is perpendicular to BQ.

BQ is the circum radius of the equilateral triangle,

BQ = a/3\sqrt3 

BQ = 20/3\sqrt3.

PQ = 302−2032\sqrt{30^2 - \frac{20}{\sqrt3}^2} = 23003\sqrt{\frac{2300}{3}}=    10√233√\frac{23}{3}.