Approximate equality is a symbol used in math to represent numbers that are close in value. It's written as '≈' and read as 'approximately equal to'.

Trigonometric functions are a type of function in math that deal with angles. They connect the measurement of an angle with the ratios of the sides of a right triangle containing that angle, and they are a basic tool for studying triangles and periodic phenomena.

The imperial system is the traditional system of measurements in the UK, with main units like feet, pounds, and gallons. Conversions are complicated, and it's mostly been replaced by the metric system now, but places like the US still use it a lot.

In the field of professional mathematics, it refers to the process of calculating the best solution under constraints.

It's a geometry term

Use the less-than sign when one number is smaller than another. Example: a = 3, b = 5, a is smaller than b.

A rational number is a number that can be written as the ratio of two integers (in fraction form). In math, integers and fractions are both generally called rational numbers.

a = 3, b = 3, a is less than or equal to b

Significant figures are all the digits from the first non-zero digit on the left to the last digit, used to reflect the measurement accuracy.

The hypotenuse is a concept unique to right triangles in geometry. It refers to the side opposite the right angle and is also the longest side of the triangle.