Tag: similarity of triangles

Questions Related to similarity of triangles

If the areas of two similar triangles are equal then the triangles :

  1. are congruent

  2. have equal length of corresponding sides

  3. (A) and (B)

  4. None of these


Correct Option: C
Explanation:

Triangles are similar if they have the same shape, but not necessarily the same size.   It is same as keeping its basic shape but either "zooming in" or out making the triangle bigger or smaller .

For triangles to be congruent if one triangle slides over the other , rotate them, and flip them over in various ways so they will exactly fit over each other.

So, if the triangles are similar, i.e. they are "zoomed-in" or "zoomed-out" versions of each other, and if they have equal area, then they are congruent, and hence have equal corresponding sides.

Sides of two similar triangles are in the ratio of $5 : 11$ then ratio of their areas is 

  1. $25 : 11$

  2. $25 : 121$

  3. $125 : 121$

  4. $121 : 25$


Correct Option: B
Explanation:

Since, ratio of area of two similar traingles = ratio of square of corresponding sides

 ratio of sides = 5 : 11
$\therefore$ ratio of their areas = $(5)^2 : (11)^2 = 25 : 121$

Sides of two similar triangles are in the ratio of $4 : 9$ then area of these triangles are in the ratio

  1. $2 : 3$

  2. $4 : 9$

  3. $81 : 16$

  4. $16 : 81$


Correct Option: D
Explanation:

$\displaystyle \because \Delta ABC\sim \Delta DEF$
$\displaystyle \therefore \dfrac{ar\Delta ABC}{ar\Delta DEF}=\dfrac{\left ( 4 \right )^{2}}{\left ( 9 \right )^{2}}=\dfrac{16}{81}=16:81.$

Similarity is represented by :

  1. $\sim$

  2. $=$

  3. $\simeq $

  4. none of these


Correct Option: A
Explanation:

$\sim$ is used to represent similarity.

So, answer is option $A.$

When the ratios of the lengths of their corresponding sides are equal, then the two figures are:

  1. similar

  2. congruent

  3. equal

  4. none of these


Correct Option: A
Explanation:

When the ratios of the lengths of their corresponding sides are equal, then the two figures are then those figure are similar by $SSS$ similarity.

Two triangles are $ABC$ and $PQR$ are similar, then symbolically it is represented as:

  1. $ABC \sim PQR$

  2. $ABC \simeq PQR$

  3. $ABC = PQR$

  4. none of these


Correct Option: A
Explanation:

Two similar triangles can be represented as $ABC∼PQR.$

All congruent figures are similar but the similar figures are not congruent.Is this statement true or false?

  1. False

  2. Both A and C

  3. True

  4. Not applicable


Correct Option: C
Explanation:

Congruent figures are of same shape and size. So they are similar but similar figures are not congruent as they might not be of the same size.
Therefore, C is the correct answer.

A tree of height 24m standing in the middle of the road casts a shadow  ofheight 16m. If at the same time a nearby pole of 48 m casts a shadow , what would the height of the shadow be?

  1. 23 m

  2. 32 m

  3. 42 m

  4. 24 m


Correct Option: B
Explanation:

If the ratio of the tree is 3 : 2 = 24 m : 16 m 
The ratio of the pole is  same so 48m : 32m
Therefore, B is the correct answer.

There were three circular tracks made in a park having the same middle point but their radii was different. These tracks will be called

  1. Not similar

  2. Similar

  3. Congruent

  4. All of the above


Correct Option: B
Explanation:

They are said to be similar as the shape is same but size differs.
Therefore, B  is the correct answer.

All ......... triangles are similar.

  1. Right angled

  2. Isoscles

  3. Equilateral

  4. Reflex


Correct Option: C
Explanation:

All Equilateral  triangles , corresponding angles are equal .So, they are similar.
Therefore, C is the correct answer.