Answer:
C) 8
Step-by-step explanation:
-5(a+3)=-55
a+3=-55/-5
a+3=11
a=11-3
a=8
Hope this answers your question :)
ANSWER
The length of a Diameter is 3.714
EXPLANATION
The circumscribed triangle is shown in the attachment.
We use the cosine ratio to find the altitude of the isosceles triangle.


Altitude =8cos(60°)
Altitude=4cm
Let the upper half of the altitude be y cm.
Then the radius of the circle is (y-4)cm
The upper radius meets the tangent at right angles.
From the smaller right triangle,






y=1.857
The diameter is 2y

=2(1.875)
The length of a Diameter is 3.714