Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Advanced 2023Paper 2
Exam
JEE Advanced
Year
2023
Paper
Paper 2
Subject
Mathematics
Chapter
Properties of Triangles

JEE Advanced 2023 · Paper 2 · Mathematics · Properties of Triangles

Consider an obtuse angled triangle ABC in which the difference...

Consider an obtuse angled triangle ABCABC in which the difference between the largest and the smallest angle is π2\dfrac{\pi}{2} and whose sides are in arithmetic progression. Suppose that the vertices of this triangle lie on a circle of radius 11.
(There are two questions based on PARAGRAPH"1"PARAGRAPH " 1 ", the question given below is one of them)
Let α\alpha be the area of the triangle ABCABC. Then the value of (64α)2( 64\alpha{)}^{2} isConsider an obtuse angled triangle ABC in which the difference between the largest and the smallest angle is (π)/(2)

Correct answer

0

Step-by-step solution

Let angle AA be obtuse angle and let sides be a−d,a,a+da - d, a, a + d

So, plotting the diagram we get,

Consider an obtuse angled triangle ABC in which the difference between the largest and the smallest angle is (π)/(2)

Now let sides be, a−d,a,a+da - d, a, a + d

Also given angle A−C=π2A - C = \dfrac{\pi}{2}

And circum radius R=1R = 1

Now by sine rule we get,

a+dsinA=asinB=a−dsinC=2\dfrac{a + d}{sin A} = \dfrac{a}{sin B} = \dfrac{a - d}{sin C} = 2

∵A=π2+C∵ A = \dfrac{\pi}{2} + C

⇒sinA=sin⁡(π2+C)⇒ sin A = \sin \left(\dfrac{\pi}{2} + C\right)

⇒sinA=cosC⇒ sin A = cos C

⇒a+d2=1−sin⁡2C⇒ \dfrac{a + d}{2} = \sqrt{1 - \sin^{2} C}

⇒(a+d2)2=1−(a−d2)2⇒ {\left(\dfrac{a + d}{2}\right)}^{2} = 1 - {\left(\dfrac{a - d}{2}\right)}^{2}

⇒2(a2+d2)4=1⇒ \dfrac{2\left({a}^{2} + {d}^{2}\right)}{4} = 1

⇒a2+d2=2...(1)⇒ {a}^{2} + {d}^{2} = 2 . . . ( 1 )

Now using cosine rule we get,

cosB=(a−d)2+(a+d)2−a22(a2−d2)cos B = \dfrac{( a - d{)}^{2} + ( a + d{)}^{2} - {a}^{2}}{2\left({a}^{2} - {d}^{2}\right)}

⇒1−sin⁡2B=2(a2+d2)−a22(a2−d2)⇒ \sqrt{1 - \sin^{2}B} = \dfrac{2\left({a}^{2} + {d}^{2}\right) - {a}^{2}}{2\left({a}^{2} - {d}^{2}\right)}

⇒1−a24=4−a22(a2−d2)(∵a2+d2=2)⇒ \sqrt{1 - \dfrac{{a}^{2}}{4}} = \dfrac{4 - {a}^{2}}{2\left({a}^{2} - {d}^{2}\right)}\left(∵ {a}^{2} + {d}^{2} = 2\right)

⇒(a2−d2)2=4−a2...(2)⇒ {\left({a}^{2} - {d}^{2}\right)}^{2} = 4 - {a}^{2} . . . ( 2 )

From (1) and (2)( 1 ) \text{ and } ( 2 )
a2=74,d2=14{a}^{2} = \dfrac{7}{4}, {d}^{2} = \dfrac{1}{4}
Area of triangle
Δ=a(a2−d2)4\Delta = \dfrac{a\left({a}^{2} - {d}^{2}\right)}{4}

α=72×64×4\alpha = \dfrac{\sqrt{7}}{2} \times \dfrac{6}{4 \times 4}

Now (64α)2=64×64×74×3616×16=4×252=1008{\left(64\alpha\right)}^{2} = 64 \times 64 \times \dfrac{7}{4} \times \dfrac{36}{16 \times 16} = 4 \times 252 = 1008

Practice Properties of Triangles on Quantrex Academy →

More from Properties of Triangles

In a triangle ABC, BC=7, AC=8, AB=α ∈ N and A=(2)/(3) . If 49 (3 C)+42= m n , where (m… JEE Main 2024Consider an obtuse angled triangle ABC in which the difference between the largest and… JEE Advanced 2023For a triangle ABC , the value of 2A + 2B + 2C is least. If its inradius is 3 and… JEE Main 2023Let ABC be the triangle with AB = 1, AC = 3 and ∠ BAC = (π)/(2) . If a circle of radius r… JEE Advanced 2022Let a, b and c be the length of sides of a triangle ABC such that (a + b)/(7) = (b +… JEE Main 2022Consider a triangle PQR having sides of lengths p, q and r opposite to the angles P, Q… JEE Advanced 2021In a triangle ABC , let AB = 23 , BC = 3 and CA = 4 . Then the value of (cotA +… JEE Advanced 2021Let (sinA)/(sinB) = ( ( A - C ))/( ( C - B )), where A, B, C are angles of a triangle ABC… JEE Main 2021Let in a right angled triangle, the smallest angle be θ . If a triangle formed by taking… JEE Main 2021If in a triangle ABC, AB = 5 units, ∠ B = ^ - 1 ((3)/(5)) and radius of circumcircle of ∆… JEE Main 2021In Δ ABC, the lengths of sides AC and AB are 12cm and 5cm, respectively. If the area of ∆… JEE Main 2021Let x, y and z be positive real numbers. Suppose x, y and z are the lengths of the sides… JEE Advanced 2020Suppose that the side lengths of a triangle are three consecutive integers and one of the… NTA Abhyas JEE Main 2020The inradius of the triangle having sides 26, 28, 30 units is NTA Abhyas JEE Main 2020The lengths of two adjacent sides of a cyclic quadrilateral are 2 units and 5 units and… NTA Abhyas JEE Main 2020Two sides of a triangle are given by the roots of the equation& x^ 2 - 2 3 x + 2 = 0 and… NTA Abhyas JEE Main 2020 Full Properties of Triangles list Properties of Triangles JEE Maths PYQsJEE Mathematics PYQs All JEE Advanced PYQs