These are also referred to as the "project management triangle", where each side represents a constraint.

Key project management responsibilities include creating clear and attainable project objectives, building the project requirements, and managing the constraints of the project management triangle, which are cost, time, scope, and quality.

After agreeing to manufacture the device for Google as the OEM, Asus was tasked with building a device that could sell for US$200 and would be "fast, cheap, and good"; according to the concept of the project management triangle, only two of these qualities can be achieved.