Three points A, B and C lie in this order on a line, and P is any
point in the plane. Use the Cosine Rule to prove the following
Three squares are drawn on the sides of a triangle ABC. Their areas
are respectively 18 000, 20 000 and 26 000 square centimetres. If
the outer vertices of the squares are joined, three more triangular
areas are enclosed. What is the area of this convex hexagon?
An observer is on top of a lighthouse. How far from the foot of the lighthouse is the horizon that the observer can see?
The Flash "movie" allows students to see the flow of function
values as the dot circles the centre point or origin. Students can
be encouraged to see the "spot" values provided by a calculator as
snap-shots of this flow.
Check that students grasp that an angle of zero is when the dot
is at (1,0), that the red line corresponds to the Sine value and
the blue line to the Cosine value.