tan A = -1/2 dengan π/2

sisi depan = 1
sisi samping = 2
sisi miring
[tex] \sqrt{ {1}^{2} + {2}^{2} } = \sqrt{5} [/tex]
[tex] \sin(a) = \frac{1}{ \sqrt{5} } \\ \cos(a) = \frac{ - 2}{ \sqrt{5} } \\ \sin(a) \times \cos(a) = \frac{1}{ \sqrt{5} } \times \frac{ - 2}{ \sqrt{5} } \\ = \frac{ - 2}{5} [/tex]