mohon bantuan yang no 1 2 3

tan 50 = p/2
[tex]r = \sqrt{ {p}^{2} + 4}[/tex]
cos 140 = cos (90 + 50) = cos 90 .cos 50 - sin 90. sin 50
cos 140 = - sin 50 =
[tex] - \frac{p}{ \sqrt{ {p}^{2} + 4 } } [/tex]