LAPEL PART A , B , C IN THE PIC BELOW USING THE LAW OF REFLECTION

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.

Calculate the volume of this regular solid. what is the volume of the cone? round your answer to the nearest hundredth

Aspring that is stretched 2.6 cm stores a potential energy of 0.053 j. what is the spring constant of this spring?