In $\triangle PQR ,$ right $-$ angled at $Q , PR + QR =25\, cm$ and $PQ =5\, cm .$ Determine the values of $\sin P, \cos P$ and $\tan P$.
Given that, $PR + QR =25$
$PQ =5$
Let $PR$ be $x$.
Therefore, $QR =25-x$
Applying Pythagoras theorem in $\triangle PQR$, we obtain
$PR ^{2}= PQ ^{2}+ QR ^{2}$
$x^{2}=(5)^{2}+(25-x)^{2}$
$x^{2}=25+625+x^{2}-50 x$
$50 x=650$
$x=13$
Therefore, $PR =13 \,cm$
$Q R=(25-13) \,cm =12\, cm$
$\sin P =\frac{\text { Side opposite to } \angle P }{\text { Hypotenuse }}=\frac{ QR }{ PR }=\frac{12}{13}$
$\cos P =\frac{\text { Side adjacent to } \angle P }{\text { Hypotenuse }}=\frac{ PQ }{ PR }=\frac{5}{13}$
$\tan P =\frac{\text { Side opposite to } \angle P }{\text { Side adjacent to } \angle P }=\frac{ QR }{ PQ }=\frac{12}{5}$
Prove that
$\frac{\sin \theta-\cos \theta+1}{\sin \theta+\cos \theta-1}=\frac{1}{\sec \theta-\tan \theta},$ using the identity
$\sec ^{2} \theta=1+\tan ^{2} \theta$
$\frac{1-\tan ^{2} 45^{\circ}}{1+\tan ^{2} 45^{\circ}}=$
State whether the following are true or false. Justify your answer.
$(i)$ The value of tan $A$ is always less than $1 .$
$(ii)$ $\sec A=\frac{12}{5}$ for some value of angle $A$.
Show that:
$(i)$ $\tan 48^{\circ} \tan 23^{\circ} \tan 42^{\circ} \tan 67^{\circ}=1$
$(ii)$ $\cos 38^{\circ} \cos 52^{\circ}-\sin 38^{\circ} \sin 52^{\circ}=0$
Evaluate the following:
$\frac{5 \cos ^{2} 60^{\circ}+4 \sec ^{2} 30^{\circ}-\tan ^{2} 45^{\circ}}{\sin ^{2} 30^{\circ}+\cos ^{2} 30^{\circ}}$