Answer:
A)60°
Step-by-step explanation:
a straight line is 180° then
if a line bisect it in to a half it become 90°
then
the exterior angle of a triangle is equal to the sum of two interior angles
this means 150°-90°=60°
Answer:55
Step-by-step explanation:
sike i lied that is so easy just try
Sorry it says plus but its times
Answer:
(a)Therefore the value of x=
(b) Therefore the value of x 
Step-by-step explanation:
Horizontal tangent line: The first order derivative of a function gives the slope of the tangent of the function. The slope of horizontal line is zero.If the slope of tangent line is zero then the tangent line is called horizontal tangent line.
(a)
Given function is,

Differential with respect to x

For horizontal tangent line, f'(x)=0
3+ 3 cos x= 0
⇒3 cos x=-3
⇒cos x=-1
⇒x = 180° 
Therefore the value of x=
(b)
Given that, the slope is 3.
Then,f'(x)=3
3+ 3 cos x= 3
⇒3 cos x= 3-3
⇒cos x=0
⇒x = 90° 
Therefore the value of x 