Why did the United States and Britain go to war in 1812?

The U.S. declared war on Britain because:

1. US Sailors were captured and forced into the british military.

2. US ships were attacked and goods were taken by british sailors.

3. NA were fighting American settlers (NA were armed by the British).

necessary and proper clause. the congress shall have power to all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states, or in any department or officer thereof.

the perimeter of a triangle is 69 cm. side a is 5 cm shorter than side b. side c is twice as long as side a. find the length of each side. i need to know how to do it in 2 equations.  

equations:

a = b-5

c = 2a

a + b + c = 69