\\Delta D E F is right angled at E. Ifm \angleD=30^\circ . What is the length (incm) of D E, if E F=2 \sqrt {3} {\cm} ?

SSC CGL 17 Aug 2017 Shift 1 Paper

Question : 70 of 100

Marks: +1, -0

\Δ D E F

is right angled at

E

. If

m ∠D=30° .

What is the length (incm) of

D E,

E F=2 √ {3} {\cm} \ ?

Solution:

According to the question,

In ΔDBF,

∠ D=30°, E F=2 √ {3} {\cm}

∴

\tan 30°= {F E}/{D E}

⇒

{1}/{\√ {3}}= {2√{3}}/{D E}

∴

D E=6 {\cm}

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