1. diketahui sin α = p , 0 < α < 90 °, maka sin 2a = .,.,.,.,? 2. kerjakan dg kuadrat sempurna , 2x²-7x-6= 0

1.
sin A = p   dan A  di kuadran 1
cos A= √(1- sin² A)
cosA = √(1 - p²)

sin 2A  = 2 sin A cos A
sin 2A = 2 (p) √(1-p²)

1) sin a = p = p/1 = de/mi => sa = √(1^2 - p^2) = √(1 - p^2)
cos a = sa/mi = √(1 - p^2)/1 = √(1 - p^2)
sin 2a = 2 sin a cos a = 2p√(1 - p^2)

2) 2x^2 - 7x - 6 = 0
2x^2 - 7x = 6
2(x^2 - 7/2 x + .... ) = 6 + ....
2(x^2 - 7/2 x + 49/16) = 6 + 2(49/16)
(x^2 - 7/2x + 49/16) = 3 + 49/16
(x - 7/4)^2 = 97/16
(x - 7/4) = ± √(97/16)
x = 7/4 ± (√97)/4
x = (7 + √97)/4 atau x = (7 - √97)/4