To achieve maximum coverage of the signal across earth, what type of line should be formed between the point where the satellite is located and the point on earth’s surface where the signal is received?

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Determine whether the following statements are true and give an explanation or counterexample. bold a. when using the shell method, the axis of the cylindrical shells is parallel to the axis of revolution. bold b. if a region is revolved about the y-axis, then the shell method must be used. bold c. if a region is revolved about the x-axis, then in principle it is possible to use the disk/washer method and integrate with respect to x or the shell method and integrate with respect to y.

Plz hurry evaluate the expression a+b where a=8 and b=19

Write the equations in logarithmic form 9^4=6,561