If tanx = 6/8 what is cos2x that 0
Options:
-8/5
8/5
-7/25
7/25
I have 20 minutes so if you could be fast, I'd really really appreciate it :D
If tan x = 6/8..... this is a 6-8-10 right triangle......then cos x = 8/10 ....so.....
cos 2x = 2cos^2x - 1
cos 2x = 2(8/10)^2 - 1
cos2x = 2 (64/100) - 1
cos2x = 128/100 - 100/100
cos 2x = 28/100 = 7/25
+956 
