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QJEEM22Ma0fea: JEE Main 2022 Mathematics - Class 11 JEEM22Ma0fea Solution: The equations of the sides and of a triangle are and…

The equations of the sides AB,BC\mathrm{AB}, \mathrm{BC} and CA\mathrm{CA} of a triangle ABC\mathrm{ABC} are 2x+y=0,x+py=15a2 x+y=0, x+\mathrm{p} y=15 \mathrm{a} and x−y=3x-y=3 respectively. If its orthocentre is (2, a),-\frac{1}{2}<\mathrm{a}<2 , then p\mathrm{p} is equal to ______________.

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JEE Main 2022 (Online) 26th July Morning Shift Mathematics - Straight Lines and Pair of Straight Lines Question 51 English Explanation

Slope of AH=a+21AH = {{a + 2} \over 1}

Slope of BC=−1pBC = - {1 \over p}

∴\therefore p=a+2p = a + 2 ...... (i)

Coordinate of C=(18p−30p+1, 15p−33p+1)C = \left( {{{18p - 30} \over {p + 1}},\,{{15p - 33} \over {p + 1}}} \right)

Slope of HC=15P−33p+1−a18p−30p+1−2=15p−33−(p−2)(p+1)18p−30−2p−2HC = {{{{15P - 33} \over {p + 1}} - a} \over {{{18p - 30} \over {p + 1}} - 2}} = {{15p - 33 - (p - 2)(p + 1)} \over {18p - 30 - 2p - 2}}

=16p−p2−3116p−32= {{16p - {p^2} - 31} \over {16p - 32}}

∵\because 16p−p2−3116p−32×−2=−1{{16p - {p^2} - 31} \over {16p - 32}} \times - 2 = - 1

∴\therefore p2−8p+15=0{p^2} - 8p + 15 = 0

∴\therefore p=3p = 3 or 55

But if p=5p = 5 then a=3a = 3 not acceptable

∴\therefore p=3p = 3

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