Question

Helpppppppp meeeee!!!!!​

Answer 1

Explanation:

`a)\\A=(1)/(2)h(a+b)\qquad\text{multiply both sides by 2}\\\\2A=2\!\!\!\!\diagup\cdot(1)/(2\!\!\!\!\diagup)h(a+b)\qquad\text{use the distrigutive property}\\\\2A=ha+hb\qquad\text{subtract}\ hb\ \text{from both sides}\\\\2A-hb=ha\qquad\text{divide both sides by}\ h\\eq0\\\\(2A-hb)/(h)=a\to \boxed{a=(2A-hb)/(h)}`

`b)\\a=(2A-hb)/(h)\\\\\text{Substitute:}\ A=19.95\ cm^2,\ b=7.8\ cm,\ h=3.5\ cm\\\\a=(2(19.95)-(3.5)(7.8))/(3.5)=(39.9-27.3)/(3.5)=(12.6)/(3.5)=3.6\\\\\boxed{a=3.6\ cm}`