What is the combined resistance of two 20
resistors connected in series?

resistors in series add algebraically (R1 + R2 + R3 + ... + Rn = Requiv) so the equivalent resistance of the 2, 2ohm resistors in series is 2 + 2 or 4ohms.

resistors in parallel add thus; 1/(1/R1 + 1/R2 + 1R3 + ... 1Rn) or for a two resistor element circuit a specialized formula of (R1*R2)/(R1 + R2) = (2*2)/(2 + 2) or 4/4 or 1 ohm

i need the answer to this too but idk it ; -;

15.3 cos 65 degrees trig