Answer:
[tex] f = 10.7 [/tex]
Step-by-step explanation:
Given ∆DEF,
<F = 36°
DF = e = 15
EF = d = 6
DE = f = ?
f can be found using the Law of Cosine as shown below:
[tex] f^2 = d^2 + e^2 - 2(d)(e)*cos(F) [/tex]
Plug in your values:
[tex] f^2 = 6^2 + 15^2 - 2(6)(15)*cos(36) [/tex]
Evaluate:
[tex] f^2 = 36 + 225 - 180*0.809 [/tex]
[tex] f^2 = 261 - 145.62 [/tex]
[tex] f^2 = 115.38 [/tex]
[tex] f = 10.74 [/tex]
[tex] f = 10.7 [/tex] (to nearest tenth)
