JAMB - Mathematics (2024 - No. 15)

PQR is a triangle such that |PQ| = |QR| = 8cm and QPR = 60º. Find the area of \(\angle\) PQR
16\(\sqrt{3}cm^2\)
16\(\sqrt{2}cm^2\)
8\(\sqrt{3}cm^2\)
16\(\sqrt{2}cm^2\)

Explanation

The area of a triangle given two sides and the included angle = \(\frac{1}{2}\) x a x b x Sin\(\theta\)

a = b = 8cm 

\(\theta\) = 60º

Area =  \(\frac{1}{2}\) x 8 x 8 x Sin 60º =  \(\frac{1}{2}\) x 64 x  \(\frac{\sqrt{3}}{2}\) ( Sin 60º =  \(\frac{\sqrt{3}}{2}\) )

=  \(\frac{64\sqrt{3}}{4}\) = 16\(\sqrt{3}cm^2\)

 

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