Answer:
The correct option is C ) 109.5°
Therefore,

Step-by-step explanation:
Given:
In Triangle DEF
d = 10
e = 18
f = 12
To Find
angle E = ?
Solution:
In Triangle DEF , Cosine Rule says

Substituting the values we get


Therefore,

............As it is in Second Quadrant
Therefore,

Let's simplify step-by-step.
−3x2−5x2(4x3−x2)(2)
Distribute:
=−3x2+−40x5+10x4
Answer:
=−40x5+10x4−3x2
Answer:
x = -25/13
Step-by-step explanation:
Subtract 41 from 16 and divide the difference by 13