IPMAT Indore 2025 · Quantitative Ability · Question 22

IPMAT Indore 2025 previous year question on Trigonometry, with the answer and a step-by-step solution.

TrigonometryGeometry and MensurationMultiple choiceMedium
In triangle ABC, AB=AC=x, \angle ABC=\theta and the circumradius is equal to y. Then \frac{x}{y} equals
  1. A
    \sin \theta
  2. B
    \cos \theta
  3. C
    2\cos \theta
  4. D
    2\sin \theta
Pick an option, then check.
Answer & solution

Answer: Option D

Step 1 — recall the extended Law of Sines. In any triangle with circumradius R,

\frac{\text{side}}{\sin \left( \text{angle opposite that side}\right)}=2R

Step 2 — pick the right side-and-angle pair. We know the angle \theta at vertex B. The side opposite B is AC, and we are told AC=x. The circumradius is y, so R=y:

\frac{AC}{\sin B}=2R \Rightarrow \frac{x}{\sin \theta}=2y

Step 3 — rearrange.

\frac{x}{y}=2\sin \theta

Note the isosceles condition AB=AC (which forces \angle ACB=\theta as well) is not actually needed — it is there to make the figure consistent.

Answer: Option 4 — 2\sin \theta

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