PQRS is a rhombus of side 16cm. The diagonal |QS| = 20cm. Calculate, correct to the nearest degree, ∠PQR

  • A 51o
  • B 64o
  • C 77o
  • D 103o
waec 2001mathematics

The correct answer is D. 103o

cos\(\alpha\) = \(\frac{10}{16}\) = 0.625

\(\alpha\) = cos-1(0.625)

= 51.3o

∠PQR = 2\(\alpha\)

= 2(51.3o)

= 102.6

= 103o

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