Question

Share

In the adjoining figure, $\angle\text{B}=90^\circ,\angle\text{BAC}=\theta,\text{BC}=\text{CD}=4\text{cm}$ and AD = 10cm. Find

1. $\sin\theta$
2. $\cos\theta.$

Hint: $\text{AB}^2=\big(\text{AD}^2-\text{BD}^2\big)=36\text{cm}^2$ $\therefore\text{AB}=6\text{cm}.$ $\text{AC}^2=\big(\text{AB}^2+\text{BC}^2\big)=52\text{cm}^2$ $\therefore\text{AC}=2\sqrt{13}\text{cm}.$ Thus, AB = 6cm and $\text{AC}=2\sqrt{13}\text{cm}.$