Resources tagged with: Sine, cosine, tangent
There are 59 NRICH Mathematical resources connected to Sine, cosine, tangent, you may find related items under Pythagoras and trigonometry.
Broad Topics > Pythagoras and trigonometry > Sine, cosine, tangent
Sine and Cosine
The sine of an angle is equal to the cosine of its complement. Can you explain why and does this rule extend beyond angles of 90 degrees?
Where Is the Dot?
A dot starts at the point (1,0) and turns anticlockwise. Can you estimate the height of the dot after it has turned through 45 degrees? Can you calculate its height?
Spokes
Draw three equal line segments in a unit circle to divide the circle into four parts of equal area.
Figure of Eight
On a nine-point pegboard a band is stretched over 4 pegs in a "figure of 8" arrangement. How many different "figure of 8" arrangements can be made ?
Octa-flower
Join some regular octahedra, face touching face and one vertex of each meeting at a point. How many octahedra can you fit around this point?
Far Horizon
An observer is on top of a lighthouse. How far from the foot of the lighthouse is the horizon that the observer can see?
Inscribed in a Circle
The area of a square inscribed in a circle with a unit radius is, satisfyingly, 2. What is the area of a regular hexagon inscribed in a circle with a unit radius?
Belt
A belt of thin wire, length L, binds together two cylindrical welding rods, whose radii are R and r, by passing all the way around them both. Find L in terms of R and r.
Three by One
There are many different methods to solve this geometrical problem - how many can you find?
8 Methods for Three by One
This problem in geometry has been solved in no less than EIGHT ways by a pair of students. How would you solve it? How many of their solutions can you follow? How are they the same or different? Which do you like best?
Doesn't Add Up
In this problem we are faced with an apparently easy area problem, but it has gone horribly wrong! What happened?
Cosines Rule
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 statement.
So Big
One side of a triangle is divided into segments of length a and b by the inscribed circle, with radius r. Prove that the area is: abr(a+b)/ab-r^2
Shape and Territory
If for any triangle ABC tan(A - B) + tan(B - C) + tan(C - A) = 0 what can you say about the triangle?
Logosquares
Ten squares form regular rings either with adjacent or opposite vertices touching. Calculate the inner and outer radii of the rings that surround the squares.
Eight Ratios
Two perpendicular lines lie across each other and the end points are joined to form a quadrilateral. Eight ratios are defined, three are given but five need to be found.
Over the Pole
Two places are diametrically opposite each other on the same line of latitude. Compare the distances between them travelling along the line of latitude and travelling over the nearest pole.
A Scale for the Solar System
The Earth is further from the Sun than Venus, but how much further? Twice as far? Ten times?
Pythagoras on a Sphere
Prove Pythagoras' Theorem for right-angled spherical triangles.
Raising the Roof
How far should the roof overhang to shade windows from the mid-day sun?
Flight Path
Use simple trigonometry to calculate the distance along the flight path from London to Sydney.
Making Maths: Clinometer
You can use a clinometer to measure the height of tall things that you can't possibly reach to the top of, Make a clinometer and use it to help you estimate the heights of tall objects.
Muggles, Logo and Gradients
Logo helps us to understand gradients of lines and why Muggles Magic is not magic but mathematics. See the problem Muggles magic.
Orbiting Billiard Balls
What angle is needed for a ball to do a circuit of the billiard table and then pass through its original position?
Sine and Cosine for Connected Angles
The length AM can be calculated using trigonometry in two different ways. Create this pair of equivalent calculations for different peg boards, notice a general result, and account for it.
Screen Shot
A moveable screen slides along a mirrored corridor towards a centrally placed light source. A ray of light from that source is directed towards a wall of the corridor, which it strikes at 45 degrees before being reflected across to the opposite wall and so on until it hits the screen.
Bend
What is the longest stick that can be carried horizontally along a narrow corridor and around a right-angled bend?
Circle Scaling
Describe how to construct three circles which have areas in the ratio 1:2:3.
Circle Box
It is obvious that we can fit four circles of diameter 1 unit in a square of side 2 without overlapping. What is the smallest square into which we can fit 3 circles of diameter 1 unit?
Squ-areas
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?
The Dodecahedron
What are the shortest distances between the centres of opposite faces of a regular solid dodecahedron on the surface and through the middle of the dodecahedron?
Circumnavigation
The sides of a triangle are 25, 39 and 40 units of length. Find the diameter of the circumscribed circle.
Small Steps
Two problems about infinite processes where smaller and smaller steps are taken and you have to discover what happens in the limit.
Dodecawhat
Follow instructions to fold sheets of A4 paper into pentagons and assemble them to form a dodecahedron. Calculate the error in the angle of the not perfectly regular pentagons you make.
Why Stop at Three by One
Beautiful mathematics. Two 18 year old students gave eight different proofs of one result then generalised it from the 3 by 1 case to the n by 1 case and proved the general result.
Farhan's Poor Square
From the measurements and the clue given find the area of the square that is not covered by the triangle and the circle.
Lying and Cheating
Follow the instructions and you can take a rectangle, cut it into 4 pieces, discard two small triangles, put together the remaining two pieces and end up with a rectangle the same size. Try it!
Round and Round
Prove that the shaded area of the semicircle is equal to the area of the inner circle.
From All Corners
Straight lines are drawn from each corner of a square to the mid points of the opposite sides. Express the area of the octagon that is formed at the centre as a fraction of the area of the square.
Diagonals for Area
Can you prove this formula for finding the area of a quadrilateral from its diagonals?
Sine Problem
In this 'mesh' of sine graphs, one of the graphs is the graph of the sine function. Find the equations of the other graphs to reproduce the pattern.
30-60-90 Polypuzzle
Re-arrange the pieces of the puzzle to form a rectangle and then to form an equilateral triangle. Calculate the angles and lengths.
Strange Rectangle 2
Find the exact values of some trig. ratios from this rectangle in which a cyclic quadrilateral cuts off four right angled triangles.
Six Discs
Six circular discs are packed in different-shaped boxes so that the discs touch their neighbours and the sides of the box. Can you put the boxes in order according to the areas of their bases?
Making Waves
Which is larger cos(sin x) or sin(cos x) ? Does this depend on x ?
Gold Again
Without using a calculator, computer or tables find the exact values of cos36cos72 and also cos36 - cos72.
At a Glance
The area of a regular pentagon looks about twice as a big as the pentangle star drawn within it. Is it?
Ball Bearings
If a is the radius of the axle, b the radius of each ball-bearing, and c the radius of the hub, why does the number of ball bearings n determine the ratio c/a? Find a formula for c/a in terms of n.
Coke Machine
The coke machine in college takes 50 pence pieces. It also takes a certain foreign coin of traditional design...