Question 99922
write expression for length of second side in terms of a
Given: second side is 4 more than half of a
so the expression would be
{{{SecondSide=4+(1/2)a}}} or
{{{SecondSide=4+a/2}}}
next
write an expression for the length of the third side in terms of a
Given: the third side is 7 less than twice a
{{{ThirdSide=2a-7}}}
last
find the perimeter if a = 3
Known: perimeter of a triangle equals the sum of all its sides
{{{perimeter=a+(4+a/2)+(2a-7)}}}
{{{perimeter=3+(4+3/2)+(2(3)-7)}}}
{{{perimeter=3+(4+1&1/2)+(6-7)}}}
{{{perimeter=3+5&1/2-1}}}
{{{perimeter=7&1/2}}} or
{{{perimeter=7.5}}}

Note: this is how the math works but with the given information a=3 there is a problem. If a=3 then the third side which is 2a-7 would result in the third side being -1. There can be no triangle with this measurement.