120832 The product of distances from any point on the hyperbola x216−y29=1 to its two asymptotes is
B Given equation is hyperbola, x216−y29=1 On comparing standerd hyperbola equation, a2=16 and b2=9 Where, x2a2−y2b2=1 d=a2b2a2+b2=16×916+9 d=14425
120833 If the equation of one asymptote of the hyperbola 14x2+38xy+20y2+x−7y−91=0 is 7x+5y−3=0, then the other asymptote is
B Given, 14x2+38xy+20y2+x−7y−91=0 We know that, euqation of the pair of line - Δ=abc+2fgh−af2−b2−ch2=0 Here, a=14, b=20,f=19, g=12, h=−72 14(20)c+2(19)(12)(−72)−14(72)2−20(12)2−c(19)2=0 81c=−243 c=−3 ∴14x2+38xy+20y2+x−7y−3=(7x+5y−3)(2x+ 4y+1). So, other asymptote is : 2x+4y+1=0
120834 The asymptotes of the hyperbola x2a2−y2b2=1, with any tangent to the hyperbola form a triangle whose area is a2tan(α). Then its eccentricity equals
A : Given, x2a2−y2 b2=1 Any tangent to the hyperbola from a triangle with the assymptotes which have always constant area and that is equal to (ab). a2tan(α)=ab tanα=ba e2=1+b2a2[e>>1] e=1+b2a2 e=1+(tanα)2 e=sec2α e=secα
120835 The equation of the hyperbola whose asymptotes are the lines 3x+4y−2=0, 2x+y+1=0 and which passes through the point (1,1) is
B Given, l1:3x+4y−2=0 l2:2x+y+1+0 Equation of hyperbola, (3x+4y−2)(2x+y+1)+k=0 On passing at point (1,1) we get - (3+4−2)(2+1+1)+k=0 20+k=0 Since, it is passes through the point (1,1) Then, (3×1+4×1−2)(2×1+1+1)+k=0 5×4+k=0 20+k=0 k=−20 Hence, equation of hyperbola is - 6x2+11xy+4y2−x+2y−22=0