The radius of the sphere decreases at the rate of 6 m/ sec
That is, 
Surface Area of the sphere of radius r is given by 
Differentiating with respect to t,


Answer:
Option A
Step-by-step explanation:
The complete question is shown in the attachment.
The sum of angles in a triangle is 180 degrees.
This implies that:

m<A+138=180
m<A=180-138=42
Now we use the sine rule to find AC=b

This implies that:


Answer:
-1/21
Step-by-step explanation:
2/3 + -5/7
Get a common denominator of 21
2/3 *7/7 = 14/21
-5/7*3/3 = -15/21
14/21 - 15/21 = -1/21
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