Let M be a point in interior of ΔABC.
Three lines are drawn through M,
parallel to triangle′s sides, thereby
producing three trapezoids. Suppose a
diagonal is drawn in each trapezoid in
such a way that the diagonals have no
common endpoints. These three
diagonals divide ABC into seven
parts, four of them being triangles.
Prove that the area of one of the four
triangles equals the sum of the areas
of the other three.
Through the vertices of the smaller
base AB of the trapezoid ABCD two
parallel lines are drawn, intersecting
the segment CD. These lines and the
trapezoid′s diagonals divide it into
seven triangles and a pentagon. Show
that the area of the pentagon equals
the sum of the areas of the three
triangles that share a common side
with the trapezoid.
Consider the quadrilateral ABCD.
The points M, N, P and Q are the
midpoints of the sides AB, BC, CD
and DA.
Let X = AP ∩ BQ, Y = BQ ∩ CM,
Q = CM ∩ DN and T= DN ∩ AP.
Prove that [XYZT] = [AQX] + [BMY]
+ [CNZ] + [DPT].
A distance of 200 km is to be covered by
car in less than 10 hours. Yash does it
in two parts. He first drives for 150 km
at an average speed of 36 km/hr,
without stopping. After taking rest for
30 minutes, he starts again and covers
the remaining distance non-stop. His
average for the entire journey
(including the period of rest) exceeds
that for the second part by 5 km/hr.
Find the speed at which he covers the
second part.
Six points A, B, C, D, E, and F are
placed on a square rigid, as shown.
How many triangles that are not
right-angled can be drawn by using 3
of these 6 points as vertices?
The Object shown in the diagram is
made by gluing together the adjacent
faces of six wooden cubes, each having
edges of length 2 cm. Find the total
surface area of the object in square
centimetres.
In the diagram, it is possible to travel
only along an edge in the direction
indicated by the arrow. How many
different routes from A to B are there
in all?
A two-digit number has the property
that the square of its tens digit plus
ten times its units digit is equal to the
square of its units digit plus ten times
its tens digit. Find all two digit
numbers which have this property, and
are prime numbers.
Let ABCD be a parallelogram. The
points M, N and P are chosen on the
segments BD, BC and CD,
respectively, so that CNMP is a
parallelogram. Let E = AN ∩ BD and
F = AP ∩ BD. Prove that
[AEF] = [DFP] + [BEN].
Let P be a point on the circumcircle of
the equilateral triangle ABC. Prove
that the projections of any point Q
onto the lines PA, PB and PC are the
vertices of an equilateral triangle.
From a point on the circumcircle of an
equilateral triangle ABC parallels to
the sides BC, CA and AB are drawn,
intersecting the sides CA, AB and BC
at the points M, N, P, respectively.
Prove that the points M, N and P are
collinear.
In how many ways can a family of 5 brothers be seated round a table
if (i) 2 brothers must seat next to each other.
(ii) 2 brothers must not seat together.
Let P_1 , P_2 , ..., P_n be a convex polygon
with the following property : for any
two vertices P_i and P_j , there exists a
vertex P_k such that the segment P_i P_j
is seen from P_k under an angle of 60°.
Prove that the polygon is an
equilateral triangle.