At 120 kts your Max drift wil be 15 degrees.
Wind is 60 degrees off track from left. Using clock rule 60 degrees is all the max drift so 090 degrees - 15 drift for wind from the left equals a heading of 075.
With wind at 60 degrees off your heading the rule is at its maximum error, and you are turning 15 degrees into wind!!! But hey the wind strength and direction are only a guess anyway.
jsf
PS Not sine and cosine directly but that's where it all comes from.