Tag: basic proportionality theorem

Questions Related to basic proportionality theorem

Basic proportionality theorem  is also known as

  1. Basic theorem

  2. Thales Theorem

  3. Potential theorem

  4. Unknown


Correct Option: B
Explanation:

Basic proportionality theorem is also known as Thales Theorem. Thales was a famous Greek mathematician who gave an important truth relating two equiangular triangles.
Therefore, C is the correct answer.

In $\triangle ABC,A-P-B, A-Q-C$ and $\overline {PQ} \parallel \overline {BC}$. If $PQ=5, AP=4$ and $PB=8$, then $BC=$.....

  1. $6$

  2. $10$

  3. $12.5$

  4. $15$


Correct Option: A

ABC is a triangle with AB = $13$ cm, BC =$14$ cm and CA=$15$ cm. AD and BE are the altitudes from A to B to BC and AC respectively. H is the point of intersection of the AD and BE. Then the ratio of $\frac { HD }{ HB } =$ 

  1. $\dfrac { 3 }{ 5 } $

  2. $\dfrac { 12 }{ 13 } $

  3. $\dfrac { 4 }{ 5 } $

  4. $\dfrac { 5 }{ 9 } $


Correct Option: A
Explanation:
According to the question,
Triangle $BEC$ and triangle $BDH$ are similar, because they have the same angles this means that the sides  of these two triangles are in the same ratio.

So,

$\dfrac{{HD}}{{BD}} = \dfrac{{CE}}{{BC}}$

Note,However that $\displaystyle \frac{{CE}}{{BC}}$=$cosC$, 

Hence$\displaystyle \frac{{HD}}{{BD}}$=$cosC$, so we proceed to find $cosC$ using the cosine rule,

${c^2} = {a^2} + {b^2} - 2ab\cos C$

${13^2} = {14^2} + {15^2} - 2(14)(15)cosC$

$\cos C = \dfrac{{{{13}^2} - {{14}^2} - {{15}^2}}}{{ - 2 \times 14 \times 15}} = \dfrac{3}{5}$

$so\, \, \dfrac{{HD}}{{HB}} = \dfrac{3}{5}$












In a triangle ABC, D and E are the point on the line segment BC and AC respectively, such that 2 BD = DC and 3 AE = 2 EC. The lines AD and BE meet at P,the line CP and AB F, then :

  1. AP:PD = 2:1

  2. BP : PE =4:

  3. BP:PE =5:4

  4. CP:PF = 7:2


Correct Option: A

Let  $ABC$  be a triangle and  $D$  and  $E$  be two points on side  $AB$  such that  $AD = BE$.  If  $D P | B C$  and  $E Q | A C,$ then $P Q | A C.$

  1. True

  2. False


Correct Option: B

If the sides a, b, c, of a triangle are such that a: b: c: :1:$\sqrt{3}$: 2, then the A:B:C is -

  1. 3 : 2 : 1

  2. 3 : 1 : 2

  3. 1 : 3 : 2

  4. 1 : 2 : 3


Correct Option: A

In any $\Delta$ABC , $4\Delta(cotA+cotB+cotC)$ is equal to 

  1. $3(a^2+b^2+c^2)$

  2. $2(a^2+b^2+c^2)$

  3. $(a^2+b^2+c^2)$

  4. none of these


Correct Option: A

$ABCD$ is a rectangl $P$ and $Q$ are poits on $AB$ and $BC$ respectively such that the area of triangle $APD=5$ area of triangle $PBQ=4$ and area of triangle $QCD=3$, all area in square units. THen the area of the triangle $DPQ$ in square units is

  1. $12$

  2. $\dfrac {20}{3}$

  3. $2\sqrt {21}$

  4. $\sqrt {21}$


Correct Option: A

If G is the centroid of $\Delta ABC$ and if area of $\Delta AGB$ is 5 sq. nits then the area of $\Delta ABC$ is 

  1. 20 sq. unit

  2. 10 sq.unit

  3. 15 sq. unit

  4. 25 sq. unit


Correct Option: A

The areas of two similar triangle are $18\ cm^{2}$ and $32\ cm^{2}$ respectively. What is the ratio of their corresponding sides?

  1. $3:4$

  2. $4:3$

  3. $9:16$

  4. $16:9$


Correct Option: A