Keisha and David each found the same value for cos0, as shown below, given sin0=-8/17. Keisha's Solution
tan²8+1 = sec²e
sin² e
cos² e
=+1=
17
cos² e
(-) + Co
+1=
1
cos² e
cos² e
+ cos²9=1
64
cos 9-1-
-- 289
15
cose=17
David's Solution
sin²+ cos² = 1
cos²8-1-(-17)
Со
cos = ±
225
289
15
cose=¹17 whose procedure is correct?
