A convex hexagon is given in which
any two opposite sides have the
following property: the distance
between their midpoints is ((√3)/2) times the
sum of their lengths. Prove that the
hexagon is equiangular.
Let H be orthocenter of ΔABC and O
its circumcenter. Prove that the vectors
OA^(→) , OB^(→) , OC^(→) and OH^(→) satisfy the
following equality:
OA^(→) + OB^(→) + OC^(→) = OH^(→)
Find distinct natural numbers from 1
to 9 such that these six equations are
satisfied simultaneously:
(1) a + bc = 20
(2) d + e + f = 20
(3) g − hi = −20
(4) adg = 20
(5) b + eh = 20
(6) c + f − i = 10
The horizontal range of a projectile
is R and the maximum height attained
by it is H. A strong wind now begins to
blow in the direction of horizontal
motion of projectile, giving it a constant
horizontal acceleration equal to g.
Under the same conditions of projection,
the new range will be
(g = acceleration due to gravity)
[Answer: R + 4H]
Three consecutive terms of an A.P form the three consecutive terms of a G.P,
If the common ratio of the G.P forms the common difference of the A.P by
adding the first term of the G.P to itself. Find the sum of the fifth term of the G.P.
Related to Q16675:
Find the number of intersection points
of graph sin x=(x/(10)).
Let′s see sin x = (x/n) with n>1.
For n≤1 there is one intersection point.
Let x=2kπ+t with k∈N ∧ t∈[0,2π]
sin x=sin t
cos x=cos t
we find the point on f(x)=sin x where its
tangent is g(x)=(x/n).
f′(x)=cos x=cos t
g′(x)=(1/n)
cos t=(1/n)
t=cos^(−1) (1/n)
sin t=(n/(√(n^2 +1)))
so that f(x) intersects with g(x),
((sin x)/x)≥(1/n)
⇒n sin x≥x
⇒n sin t≥2kπ+t
⇒k≤((n sin t −t)/(2π))=(((n^2 /(√(n^2 +1)))−cos^(−1) (1/n))/(2π))
k_(max) =⌊(((n^2 /(√(n^2 +1)))−cos^(−1) (1/n))/(2π))⌋
number of intersecting points is
m=2×2(k_(max) +1)−1=4k_(max) +3
for n=10
k_(max) =⌊(((n^2 /(√(n^2 +1)))−cos^(−1) (1/n))/(2π))⌋
=⌊((((10^2 )/(√(10^2 +1)))−cos^(−1) (1/(10)))/(2π))⌋=⌊1.35⌋=1
⇒m=4×1+3=7
for n=20
k_(max) =⌊((((20^2 )/(√(20^2 +1)))−cos^(−1) (1/(20)))/(2π))⌋=⌊2.94⌋=2
⇒m=4×2+3=11