Numbers and maths

Python as a calculator

Python does arithmetic with these operators:

Operator	Meaning	Example	Result
+ -	add, subtract	7 - 2	5
*	multiply	3 * 4	12
/	divide	7 / 2	3.5
//	divide, rounding down	7 // 2	3
%	remainder	7 % 2	1
**	power	2 ** 3	8

Whole numbers like 4 are ints. Numbers with a decimal point like 0.25 are floats. The usual order of operations applies, and parentheses group: (1 + 2) * 3 is 9.

Floats are stored in binary, so some decimals come out a hair off: 0.1 + 0.2 prints 0.30000000000000004. That's normal, and you'll learn to round for display in the next step.

The math module

More maths lives in the math module. Write import math at the top of the program, then use math.pi, math.sqrt(x) (square root), math.sin(x) and friends.

Robots measure angles in radians, not degrees. A full turn is 360°, or $2\pi$ radians, so:

$$\text{radians} = \text{degrees} \times \frac{\pi}{180}$$

Your task

The arm's upper arm is 0.30 m long and its forearm 0.25 m. The starter stores them in upper_arm and forearm.

1. Set reach to the two lengths added together. Use the variables, not the numbers.
2. Set angle_rad to angle_deg converted to radians.
3. Set diagonal to the length of the diagonal across a square table 0.8 m on each side: $\sqrt{0.8^2 + 0.8^2}$.