Scalar products

There are 11 NRICH Mathematical resources connected to Scalar products
Cubestick
problem
Favourite

Cubestick

Age
16 to 18
Challenge level
filled star filled star empty star
Stick some cubes together to make a cuboid. Find two of the angles by as many different methods as you can devise.
Flexi Quads
problem
Favourite

Flexi quads

Age
16 to 18
Challenge level
filled star empty star empty star
A quadrilateral changes shape with the edge lengths constant. Show the scalar product of the diagonals is constant. If the diagonals are perpendicular in one position are they always perpendicular?
Walls
problem

Walls

Age
16 to 18
Challenge level
filled star filled star filled star
Plane 1 contains points A, B and C and plane 2 contains points A and B. Find all the points on plane 2 such that the two planes are perpendicular.
Pythagoras on a Sphere
problem

Pythagoras on a sphere

Age
16 to 18
Challenge level
filled star filled star filled star
Prove Pythagoras' Theorem for right-angled spherical triangles.
Quaternions and Reflections
problem

Quaternions and reflections

Age
16 to 18
Challenge level
filled star filled star filled star
See how 4 dimensional quaternions involve vectors in 3-space and how the quaternion function F(v) = nvn gives a simple algebraic method of working with reflections in planes in 3-space.
Bond angles
problem

Bond angles

Age
16 to 18
Challenge level
filled star filled star filled star
Think about the bond angles occurring in a simple tetrahedral molecule and ammonia.
Coordinated crystals
problem

Coordinated crystals

Age
16 to 18
Challenge level
filled star empty star empty star
Explore the lattice and vector structure of this crystal.
Cross with the Scalar product
problem

Cross with the scalar product

Age
16 to 18
Challenge level
filled star filled star empty star
Explore the meaning of the scalar and vector cross products and see how the two are related.
Flexi Quad Tan
problem

Flexi quad tan

Age
16 to 18
Challenge level
filled star empty star empty star
As a quadrilateral Q is deformed (keeping the edge lengths constnt) the diagonals and the angle X between them change. Prove that the area of Q is proportional to tanX.
Air Routes
problem

Air routes

Age
16 to 18
Challenge level
filled star filled star empty star
Find the distance of the shortest air route at an altitude of 6000 metres between London and Cape Town given the latitudes and longitudes. A simple application of scalar products of vectors.