In\( ∠ PQR, P\hat{Q}P = 84^°, |Q\hat{P}R |= 43^°\) and |PQ| = 5cm. Find /QR/...

MATHEMATICS
WAEC 2003

In\( ∠ PQR, P\hat{Q}P = 84^°, |Q\hat{P}R |= 43^°\) and |PQ| = 5cm. Find /QR/ in cm, correct to 1 decimal place.

  • A. 3.4
  • B. 4.3
  • C. 5.9
  • D. 6.2

Correct Answer: B. 4.3

Explanation

Using the sine rule

\(\frac{|QR|}{sinP}=\frac{|PQ|}{sinR}\\

\frac{x}{sin43^o}=\frac{5}{sin53^o}\\

x = \frac{5\times sin43^o}{sin53^o}\\

=\frac{5\times 0.6820}{0.7986}\\

=4.3\)



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