Remark
Good golfers never slice the ball. They occasionally may hook it but they seldom if ever slice it. If he only slices it 10 years and his shot is 275 yards from the tee, his straight line distance from the hole is hardly noticeable from 478 - 275 = 203. It will take a couple of decimal places I would think to notice the difference.
If he shot the first shot straight down the middle of the fairway, his distance to the flag would be exactly 203 yards. Since he is 10 yards off the center line. You need to employ the Pythagorean theorem twice. The first time to figure out what that slice has cost him. His tee shot is 275 yards. The straight line distance is (b).
a=10
b = ??
c = 275
a^2 + b^2 = c^2
10^2 + b^2 = 275^2
100 + b^2 = 75625
b^2 = 76625 - 100
b^2 = 76525
b = sqrt(76525)
b = 274.82
So his straight line distance is 475 - 274.82 = 200.18
Now what you need to do is take another shot from 10 yards of the straight line distance.
a = straight line distance = 200.18
b = 10
c = actual distance
a^2 + b^2 = c^2
200.18^2 + 100 = c^2
40072.78 + 100 = c^2
c = sqrt(40172.78)
c = 200.43 yards. Answer