What is equation?i dont what that means can u help

The anwser cause i do not understand just plez

Analyze the diagram below and complete the instructions that follow. how to find tan

Acentral angle measuring 160 degrees intercepts an arc in a circle whose radius is 4. what is the length of the arc the circle formed by this central angle? round the length of the arc to the nearest hundredth of a unit. a) 4.19 units b) 6.28 units c) 12.57 units d) 12.57 square units