Question

Please help me with this trigonometry question. Brainliest available.

Answer 1

Considering the angle a by cosine rule
11^2 =7 ^2 +15^2 - 2(7)(15)cos(a)
When you do the maths,
Cos(a) =153/210 =0.729
a= cos inverse of 0.729
a=43 degrees


Considering angle b
7^2=15^2 +11^2 -2(11)(15) cos(b)
This will result in cos(b) =297/330=0.9
b= cos inverse of 0.9 = 25.8 degrees


Considering angle c
15^2=7^2 +11^2 - 2(11)(7) cos(c)
Cos(c) will be = -55/154 = -0.357
c= cos inverse of -0.357=110.9

Comparing the angles a,b and c,
C is the largest size in the triangle with an angle of 110.9 degrees

Am I right please ??