Question

4.

Triangle DEF is shown below.
E
19-6 m
I
10-4 m
13-2 m
D
It has sides of length 10.4metres, 13.2metres and 19.6metres.
Calculate the size of angle EDF.

Answer 1

111.75 degrees

Explanation:

EDF = cos^-1((b²+c²-a²)/2bc)

EDF = cos^-1((10.4²+19.6²-13.2²)/2(10.4)(19.6))

EDF = 111.75 degrees