Coordinate Geometry Solving
A. Angle between straight lines 2x2+3y2−7xy=0
Ye ek pair of straight lines ka equation hai (ax2+2hxy+by2=0). Yahan a=2,b=3,h=−7/2.
Formula:
tanθ=2+32(−7/2)2−(2)(3)=5249/4−6
tanθ=5225/4=52(5/2)=1⟹θ=4π
Match: (iii) 4π
B. Intersection angle of circles x2+y2+x+y=0 and x2+y2+x−y=0
Dono circles ke centers C1(−1/2,−1/2) aur C2(−1/2,1/2) hain aur radii r1=r2=1/2 hain.
Intersection angle cosθ ka formula:
cosθ=2r1r2d2−r12−r22
Yahan d2=(−1/2−(−1/2))2+(1/2−(−1/2))2=1.
cosθ=2(1/2)(1/2)1−1/2−1/2=10=0⟹θ=2π
Match: (iv) 2π
C. Area of circle centred at (1,2) passing through (4,6)
Pehle radius (r) nikalte hain distance formula se:
r=(4−1)2+(6−2)2=32+42=5
Area of circle:
Match: (ii) <spanclass="math−inline"data−math="425π"data−index−in−node="117">25\pi</span></strong></p>
<p data-path-to-node="20"><strong data-path-to-node="20" data-index-in-node="0">D. Intersection angle of <span class="math-inline" data-math="y^2=4x" data-index-in-node="25">y2=4x</span> and <span class="math-inline" data-math="x^2=32y" data-index-in-node="36">x2=32y</span> at <span class="math-inline" data-math="(16, 8)" data-index-in-node="47">(16,8)</span></strong></p>
<p data-path-to-node="20">Dono curves ko differentiate karke slopes (<span class="math-inline" data-math="m_1, m_2" data-index-in-node="98">m1,m2</span>) nikalte hain:</p>
<ol start="1" data-path-to-node="21">
<li>
<p data-path-to-node="21,0,0"><span class="math-inline" data-math="2y \frac{dy}{dx} = 4 \implies m_1 = \frac{2}{y} = \frac{2}{8} = \frac{1}{4}" data-index-in-node="0">2ydxdy=4⟹m1=y2=82=41</span></p>
</li>
<li>
<p data-path-to-node="21,1,0"><span class="math-inline" data-math="2x = 32 \frac{dy}{dx} \implies m_2 = \frac{x}{16} = \frac{16}{16} = 1" data-index-in-node="0">2x=32dxdy⟹m2=16x=1616=1</span></p>
<p data-path-to-node="21,1,0">Angle formula:</p>
<div data-path-to-node="21,1,1">
<div class="math-block" data-math="\tan \theta = \left| \frac{m_2 - m_1}{1 + m_1m_2} \right|">\tan \theta = \left| \frac{m_2 - m_1}{1 + m_1m_2} \right|</div></div><divdata−path−to−node="21,1,2"><divclass="math−block"data−math="tanθ=1+(1)(1/4)1−1/4=5/43/4=53⟹θ=tan−1(53)">\tan \theta = \left| \frac{1 - 1/4}{1 + (1)(1/4)} \right| = \frac{3/4}{5/4} = \frac{3}{5} \implies \theta = \tan^{-1}\left(\frac{3}{5}\right)$$