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3. A man 1.5 m tall observes that the angle ofelevation of the top of a building is 60°. Ifhe stands 50 m away from the base of thebuilding, find its height to the nearest metre.​

Answer»

Height \:of \:a \:man (AB) = 1.5 \:m

Height \:of \:the \: building (CE) = CD + DE \\= (1.5m + x) \:m

Distance \: between \: man \: to \:base  \\of \: of \:the \: building (BC) = 50 \:m

Angle \:of \: elevation = 60\degree

In \:triangle ADE, \:we \:have , \\tan \:60\degree = \frac{ED}{AD} \\\implies \sqrt{3} = \frac{x}{50} \\\implies 50\sqrt{3} = x

Height \: of \:the \: building = x + CD \\= 50\sqrt{3} + 1.5 \\= 50\times 1.732 + 1.5 \\= 86.6 + 1.5 \\=88.1 \:m

THEREFORE.,

\red {Height \: of \:the \: building}\green {=88.1 \:m}

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