# Math Help - hi there, can someone expand please?

1. ## hi there, can someone expand please?

hello again.

another equation which i am having some difficulty with:

two alternating currents I1 and I2 flow into a circuit node,the output current I is given by adding I1 and I 2.

find I and t, when I1 and I2 are as follows :

I1=5sin(50t +Pi/3)

I2=6cos50t.

so i can see from the 1st equation its obviously a compound angle formula i need to use. ie sin(a+b)=sina.sinb+cosa.cosb

so moving on i get sin50t x sin pi/3 + cos50t x cospi/3 which evetually comes out as 3.85t by my calculations ie I1 =3.85t?

i'm not sure really where to go with this or how to transform I2, it may be the cosine rule which is cosa.cosb +sina.sinb buts thats it i'm afraid my lesson book is not very clear either to be honest,so all in all toiling and getting uptight with this.

any hints appreciated

2. $I = I_1 + I_2 = 5\sin(50t + \frac{\pi}{3}) + 6\cos(50t)$