# Measurement and Trigonometry - October 2004, Stage 4&5

## Problems

### Square It

##### Stage: 3 and 4 Challenge Level:

Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a square.

### Salinon

##### Stage: 4 Challenge Level:

This shape comprises four semi-circles. What is the relationship between the area of the shaded region and the area of the circle on AB as diameter?

### Sliced

##### Stage: 4 Challenge Level:

An irregular tetrahedron has two opposite sides the same length a and the line joining their midpoints is perpendicular to these two edges and is of length b. What is the volume of the tetrahedron?

### Tubular Stand

##### Stage: 4 Challenge Level:

If the radius of the tubing used to make this stand is r cm, what is the volume of tubing used?

### Bend

##### Stage: 5 Challenge Level:

What is the longest stick that can be carried horizontally along a narrow corridor and around a right-angled bend?

### Gosh Cosh

##### Stage: 5 Challenge Level:

Explore the hyperbolic functions sinh and cosh using what you know about the exponential function.

### Complex Sine

##### Stage: 5 Challenge Level:

Solve the equation sin z = 2 for complex z. You only need the formula you are given for sin z in terms of the exponential function, and to solve a quadratic equation and use the logarithmic function.