Choose the correct answer from the given four options:
If $ S $ is a point on side $ P Q $ of a $ \triangle P Q R $ such that $ P S=Q S=R S $, then
(A) $ \mathrm{PR}, \mathrm{QR}=\mathrm{RS}^{2} $
(B) $ \mathrm{QS}^{2}+\mathrm{RS}^{2}=\mathrm{QR}^{2} $
(C) $ \mathrm{PR}^{2}+\mathrm{QR}^{2}=\mathrm{PQ}^{2} $
(D) $ \mathrm{PS}^{2}+\mathrm{RS}^{2}=\mathrm{PR}^{2} $
Given:
\( S \) is a point on side \( P Q \) of a \( \triangle P Q R \) such that \( P S=Q S=R S \).
To do:
We have to choose the correct answer.
Solution:
Let $\angle PRS=\angle 1, \angle RPS=\angle 2, \angle SRQ=\angle 3$ and $\angle RQS =\angle 4$
$P S=Q S=R S$
In $\triangle P S R$,
$P S=R S$
This implies,
$\angle 1=\angle 2$
Similarly,
In $\triangle R S Q$,
$\angle 3=\angle 4$ (Corresponding angles)
In $\triangle P Q R$,
$\angle P+\angle Q+\angle R=180^{\circ}$
$\angle 2+\angle 4+\angle 1+\angle 3=180^{\circ}$
$\angle 1+\angle 3+\angle 1+\angle 3 =180^{\circ}$
$2(\angle 1+\angle 3) =180^{\circ}$
$\angle 1+\angle 3=\frac{180^{\circ}}{2}$
$=90^{\circ}$
$\angle R =90^{\circ}$
Therefore,
In $\triangle P Q R$, by Pythagoras theorem,
$P R^{2}+Q R^{2}=P Q^{2}$.
Related Articles
- In a \( \Delta \mathrm{PQR}, \mathrm{PR}^{2}-\mathrm{PQ}^{2}=\mathrm{QR}^{2} \) and \( \mathrm{M} \) is a point on side \( \mathrm{PR} \) such that \( \mathrm{QM} \perp \mathrm{PR} \).Prove that \( \mathrm{QM}^{2}=\mathrm{PM} \times \mathrm{MR} \).
- Construct a triangle \( \mathrm{PQR} \) in which \( \mathrm{QR}=6 \mathrm{~cm}, \angle \mathrm{Q}=60^{\circ} \) and \( \mathrm{PR}-\mathrm{PQ}=2 \mathrm{~cm} \).
- In figure below, \( \mathrm{PQR} \) is a right triangle right angled at \( \mathrm{Q} \) and \( \mathrm{QS} \perp \mathrm{PR} \). If \( P Q=6 \mathrm{~cm} \) and \( P S=4 \mathrm{~cm} \), find \( Q S, R S \) and \( Q R \)."
- Choose the correct answer from the given four options:If in two triangles \( \mathrm{DEF} \) and \( \mathrm{PQR}, \angle \mathrm{D}=\angle \mathrm{Q} \) and \( \angle \mathrm{R}=\angle \mathrm{E} \), then which of the following is not true?(A) \( \frac{\mathrm{EF}}{\mathrm{PR}}=\frac{\mathrm{DF}}{\mathrm{PQ}} \)(B) \( \frac{\mathrm{DE}}{\mathrm{PQ}}=\frac{\mathrm{EF}}{\mathrm{RP}} \)(C) \( \frac{\mathrm{DE}}{\mathrm{QR}}=\frac{\mathrm{DF}}{\mathrm{PQ}} \)(D) \( \frac{E F}{R P}=\frac{D E}{Q R} \)
- In \( \Delta \mathrm{PQR}, \mathrm{PD} \perp \mathrm{QR} \) such that \( \mathrm{D} \) lies on \( \mathrm{QR} \). If \( \mathrm{PQ}=a, \mathrm{PR}=b, \mathrm{QD}=c \) and \( \mathrm{DR}=d \), prove that \( (a+b)(a-b)=(c+d)(c-d) \).
- \( A \) and \( B \) are respectively the points on the sides \( P Q \) and \( P R \) of a triangle \( P Q R \) such that \( \mathrm{PQ}=12.5 \mathrm{~cm}, \mathrm{PA}=5 \mathrm{~cm}, \mathrm{BR}=6 \mathrm{~cm} \) and \( \mathrm{PB}=4 \mathrm{~cm} . \) Is \( \mathrm{AB} \| \mathrm{QR} \) ? Give reasons for your answer.
- In \( \triangle \mathrm{PQR}, \quad \angle \mathrm{P}=\angle \mathrm{Q}+\angle \mathrm{R}, \mathrm{PQ}=7 \) and \( \mathrm{QR}=25 \). Find the perimeter of \( \triangle \mathrm{PQR} \).
- Classify the following reactions into different types, giving a reason(a) \( C a O(s)+S i O_{2}(g) \quad \longrightarrow \quad C a S i O_{3}(s) \)(b) \( K O H(a q)+H C l(a q) \quad \longrightarrow \quad K C l(a q)+H_{2} O(l) \)(c) \( \mathrm{Cu}(\mathrm{s})+2 \mathrm{AgNO}_{3}(\mathrm{aq}) \longrightarrow \mathrm{Cu}\left(\mathrm{NO}_{2}\right)_{2}(\mathrm{aq})+2 \mathrm{Ag}(\mathrm{s}) \)(d) \( B a C O_{3}(s) \stackrel{\text { heat }}{\longrightarrow} B a O(s)+C O_{2}(g) \)
- Choose the correct answer from the given four options:If in two triangles \( \mathrm{ABC} \) and \( \mathrm{PQR}, \frac{\mathrm{AB}}{\mathrm{QR}}=\frac{\mathrm{BC}}{\mathrm{PR}}=\frac{\mathrm{CA}}{\mathrm{PQ}} \), then(A) \( \triangle \mathrm{PQR} \sim \triangle \mathrm{CAB} \)(B) \( \triangle \mathrm{PQR} \sim \triangle \mathrm{ABC} \)(C) \( \triangle \mathrm{CBA} \sim \triangle \mathrm{PQR} \)(D) \( \triangle \mathrm{BCA} \sim \triangle \mathrm{PQR} \)
- In figure below, \( \mathrm{PA}, \mathrm{QB}, \mathrm{RC} \) and \( \mathrm{SD} \) are all perpendiculars to a line \( l, \mathrm{AB}=6 \mathrm{~cm} \), \( \mathrm{BC}=9 \mathrm{~cm}, C D=12 \mathrm{~cm} \) and \( S P=36 \mathrm{~cm} \). Find \( P Q, Q R \) and \( R S \)."
- In a quadrilateral \( \mathrm{ABCD}, \angle \mathrm{A}+\angle \mathrm{D}=90^{\circ} \). Prove that \( \mathrm{AC}^{2}+\mathrm{BD}^{2}=\mathrm{AD}^{2}+\mathrm{BC}^{2} \) [Hint: Produce \( \mathrm{AB} \) and DC to meet at E]
- \( \triangle \mathrm{ABC} \sim \triangle \mathrm{PQR} \). If \( 2 \angle \mathrm{P}=3 \angle \mathrm{Q} \) and \( \angle C=100^{\circ} \), find \( \angle B \).
- 10. Construct \( \triangle \mathrm{PQR} \) with \( \mathrm{PQ}=4.5 \mathrm{~cm}, \angle \mathrm{P}=60^{\circ} \) and \( \mathrm{PR}=4.5 \mathrm{~cm} . \) Measure \( \angle \mathrm{Q} \) and \( \angle \mathrm{R} \). What type of a triangle is it?
- 1. Why does the colour of copper sulphate solution change when an iron nail is dipped in it?2. Give an example of a double displacement reaction other than the one given in Activity 1.10.3. Identify the substances that are oxidised and the substances that are reduced in the following reactions.\[\begin{array}{l}\text { (i) } 4 \mathrm{Na}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{Na}_{2} \mathrm{O}(\mathrm{s}) \text { (ii) } \mathrm{CuO}(\mathrm{s})+\mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{Cu}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})\end{array}\]
Kickstart Your Career
Get certified by completing the course
Get Started