Question

In $\Delta$ PQR, right-angled at Q(see Fig. 8.20), PQ = 3 cm and PR = 6 cm. Determine $\angle QPR$ and $\angle PRQ$.

Answer 1

$PR=\sqrt{3^2+5^2}=\sqrt{45}=3\sqrt{5}$

${\theta }_1={\sin }^{-1}\frac{6}{3\sqrt{5}}$ and ${\theta }_2={\sin }^{-1}\frac{3}{3\sqrt{5}}$

or

${\theta }_1={\sin }^{-1}\frac{2}{\sqrt{5}}$ and ${\theta }_2={\sin }^{-1}\frac{1}{\sqrt{5}}$