Skip to content
dronacharya.ai
← JEE Advanced 2021 · Paper 2
MathematicsNumerical+2Question 46 of 57

JEE Advanced 2021 · Paper 2, Mathematics question 8

Passage

Question Stem for Question Nos. 7 and 8

Consider the region R={(x,y)∈R×R:x≥0 and y2≤4−x}R = \{(x, y) \in \mathbb R \times \mathbb R : x \ge 0 \text{ and } y^2 \le 4 - x\}. Let F\mathcal F be the family of all circles that are contained in RR and have centers on the xx-axis. Let CC be the circle that has largest radius among the circles in F\mathcal F. Let (α,β)(\alpha, \beta) be a point where the circle CC meets the curve y2=4−xy^2 = 4 - x.

The value of α\alpha is ____.

Answer and worked solution

Official answer: 1.95

From the previous part, CC has centre (32,0)\left(\frac32,0\right) and touches y2=4−xy^2=4-x at x=h+12x=h+\frac12. So
α=32+12=2.\alpha=\frac32+\frac12=2.