Jika sin x + cos x =√2 , tan x = 1 , tentukan sin x . cos x =
whongaliemsin x + cos x = √2 ....kedua ruas pangkatkan 2 (sin x + cos x)² = (√2)² sin² x + 2.sin x .cos x + cos² x = 2 1 + 2.sin x .cos x = 2 .....(ingat : sin² x + cos² x = 1) 2.sin x . cos x = 2 - 1 2 sin x . cos x = 1 sin x . cos x =
(sin x + cos x)² = (√2)²
sin² x + 2.sin x .cos x + cos² x = 2
1 + 2.sin x .cos x = 2 .....(ingat : sin² x + cos² x = 1)
2.sin x . cos x = 2 - 1
2 sin x . cos x = 1
sin x . cos x =