Question 64960
Solve A = 1/2 h(b1 + b2) for b2

First lets divide both sides by 1/2h or h/2 (h cannot be zero) and we get:
A/(h/2)=b1+b2 

We can show that A/(h/2)=2A/h so we have:

2A/h=b1+b2  subtract b1 from both sides and we get
2A/h-b1=b2 or 
 b2=(2A-b1h)/h

ck
A=h/2(b1+(2A-b1h)/h)) simplifying we get:
A=h/2(b1h+(2A-b1h))/h or
A=(b1h+2A-b1h)/2
A=2A/2=A


Hope this helps.  Happy holidays.---ptaylor