Question

if a/b=4/5 and b/c=15/16 then,the value of (c2- a2)/(c2+a2) is

Answer 1

Given, a/b = 4/5 and b/c = 15/16
we have to find (c² - a²)/(c² + a²).

now, (c² - a²)/(c² + a²)

= c²{1 - (a/c)²}/c²{ 1 + (a/c)²}

= {1 - (a/c)²}/{1 + (a/c)²} ...........(1)

so, we have to find a/c at first,

a/b = 4/5 and b/c = 15/16 .

(a/b) × (b/c) = 4/5 × 15/16 = 3/4

a/c = 3/4 ..........(2)

now, put equation (2) in equation (1),
= {1 - (3/4)²}/{1 + (3/4)²}

= {1 - 9/16}/{1 + 9/16}

= (16 - 9)/(16 + 9)

= 7/25

hence, answer is 7/25

Answer 2

Answer:

Here,a/b =4/5 and b/c=15/16

So we will multiply a/b*b/c

=> a/b*b/c = 4/5*15/16

=>a/c = 3/4

Then,

C^2-a^2/c^2+a^2

=> 4^2-3^2/4^2+3^2

=>16-9/16+9

=>7/25

Hence,answer is 7/25