Question

In triangle Abc Ab :Bc 3:4 Bc:Ac=5:4. (a) If Ab=30cm what is the length of bc ? (b) If bc =20cm what is the length of Ab and Ac. (c) what is Ab:Bc:Ac?​

Answer 1

Answer:

It is given that,AB/BC=3/4

AB=30cm

so 30/BC=3/4

BC=30×4/3

BC=40 cm

Answer 2

In Triangle ABC, AB : BC = 3 : 4 , BC : AC = 5 : 4.

1. (a) If AB = 30cm, We have to find the length of BC
2. (b) If BC = 20cm, We have to find the length AB and BC.
3. (c) AB : BC = AC = ?

(a) Here, AB : BC = 3 : 4

Let proportionality constant is x.

⇒AB = 3x and BC = 4x

Given, AB = 3x = 30 cm

⇒x = 10 cm

so, BC = 4x = 4 × 10 cm = 40 cm

(b) Here, BC : AC = 5 : 4

Let proportionality constant is p.

⇒BC = 5p and AC = 4p

Given, BC = 5p = 20 cm

⇒p = 4 cm

so, AC = 4p = 4 × 4 cm = 16 cm

(c) Here, AB : BC = 3 : 4 and BC : AC = 5 : 4.

We have to just make BC equal in both ratios.

so, multiply 5 in first ratio and multiply 4 in 2nd ratio.

we get,

AB : BC = 3 × 5 : 4 × 5

BC : AC = 4 × 5 : 4 × 4

⇒AB : BC : CA = (3 × 5) : (4 × 5) : (4 × 4)

= 15 : 20 : 16

Also read similar questions : In a triangle ABC AB:BC=3:4 BC :AC =5:4

A) If AB=30 degre .what is the length of BC

B ) what is AB:BC:AC

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