Choose the Correct Formula to Solve the Problem $$O P = V _ { 1 } ^ { 2 } + V _ { 2 } ^ { 2 } + 2 \left( V _ { 1 } \right) \left( V _ { 2 } \right) \cos \theta$$

Choose the correct formula to solve the problem. $$O P = V _ { 1 } ^ { 2 } + V _ { 2 } ^ { 2 } + 2 \left( V _ { 1 } \right) \left( V _ { 2 } \right) \cos \theta$$ $$I = E / R$$ $$E = I R$$ $$R = E / I$$ $P = I ^ { 2 } R$ $$I = P / E$$ $$E = P / I$$ $$R = E ^ { 2 } / p$$ $$P = E ^ { 2 } / R$$ $$I = \sqrt { P / R }$$ $$E = \sqrt { P R }$$ $$R = P / I _ { I ^ { 2 } }$$ A 500-watt electric iron is connected to 120 volts. How many amps of current to three decimal places does the iron take?