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E-learning matematika, GRATIS

2. Buktikan bahwa cos ( ) + cos ( ) = cos a
Bukti :
Ruas kiri = cos ( ) + cos ( )

=( cos cos a – sin sin a ) + ( cos cos a + sin sin a )

= 2 cos cos a

= 2( ) cos a
= cos a
= Ruas kanan (terbukti)
0
3. Hitung nilai Sin 75 tanpa menggunakan kalkulator atau tabel matematika
Jawab :
0
0
0
Sin 75 = Sin(45 + 30 )
0
0
0
0
= sin 45 cos 30 + cos 45 sin 30
= ( )( ) + ( )( )
= +
= ( + )
4. Diketahui sin A = ,cos B = ,sudut A dan B lancip.Hitunglah nilai
tan( A – B )!
Jawab :

AP =
=
=
= = 4 tan A =

RS =
=
=
= = 5 tan B =

Tan (A – B ) =

=

=

= x

=

MGMP Matematika SMK kota Pasuruan