TS EAMCET · Maths · Properties of Triangles

In a $∆ A B C,$ if $(a - b) (s - c) = (b - c) (s - a)$ then $r_{1}, r_{2}$ and $r_{3}$ are

A in arithmetic progression
B in geometric progression
C in harmonic progression
D equal

Verified Solution

Answer & Solution

Correct Answer

(A) in arithmetic progression

Step-by-step Solution

Detailed explanation

Given:a-bs-c=b-cs-a ⇒s-cb-c=s-aa-b ⇒s-cs-c-s-b=s-as-b-s-a As, r1=∆s-a,r2=∆s-b,r3=∆s-c, where ∆ represents area. ⇒∆r3∆r3-∆r2=∆r1∆r2-∆r1 ⇒r2r2-r3=r2r1-r2 ⇒r1-r2=r2-r3…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Match the items of List-I with those of the items of List-II

	List- $I$		List- $II$
A	Range of $\sec^{- 1} [1 + \cos^{2} x]$ , $[\cdot]$ denote greatest integer function	I	odd function
B	Domain of $f (x)$ where $f (x + \frac{1}{x}) = x^{2} + \frac{1}{x^{2}}$	II	$\{0, \frac{1}{2}\}$
C	$f (x + y) = f (x) + f (y); f (1) = 5$	III	$\{\sec^{- 1} 5, \sec^{- 1} 4\}$
D	$\sin^{- 1} x - \cos^{- 1} x + \sin^{- 1} (1 - x) = 0 \Rightarrow x \in$	IV	$R$
		V	$\{\sec^{- 1} 1, \sec^{- 1} 2\}$

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In a ∆ABC, if a-bs-c=b-cs-a then r1, r2 and r3 are

Step-by-step Solution

In a $∆ A B C,$ if $(a - b) (s - c) = (b - c) (s - a)$ then $r_{1}, r_{2}$ and $r_{3}$ are