Online Course Discussion Forum

hello I need some help on II-A 8.26 (b)

 
 
Picture of Bober Yang
hello I need some help on II-A 8.26 (b)
by Bober Yang - Saturday, 7 November 2020, 4:03 PM
 

I don't know how to find the value because it did not give me any so i don't know where to start

can i get some help thanks

 
Picture of Bober Yang
Re: hello I need some help on II-A 8.26 (b)
by Bober Yang - Saturday, 7 November 2020, 4:37 PM
 

also I need help on 8.27

Picture of Dr. Kevin Wang
Re: hello I need some help on II-A 8.26 (b)
by Dr. Kevin Wang - Saturday, 7 November 2020, 9:48 PM
 

8.27 needs to find the area of a trapezoid.  We already know its two bases, so it remains to find the height.  In an isosceles trapezoid, the segment connecting the midpoints of the two bases is perpendicular to both bases.

8.28 The assumption that $CE$ is tangent to the circle gives too much away.

8.30 Draw a diagram, as precise as possible.  Use Power of a Point to get $AD^2 = BC\cdot BD$, and solve an equation.

Picture of Bober Yang
Re: hello I need some help on II-A 8.26 (b)
by Bober Yang - Saturday, 7 November 2020, 4:49 PM
 

Honestly I also don't get 8.30 and 8.28 sorry i have to put them seperately

Picture of Dr. Kevin Wang
Re: hello I need some help on II-A 8.26 (b)
by Dr. Kevin Wang - Saturday, 7 November 2020, 9:38 PM
 

The region $C$ is the largest, and we want to minimize $C-(A+B)$,  Since this value can be negative, it means we want $A+B$ to cancel out $C$ and the remaining portion is as large as possible.  Neither $A$ nor $B$ can be larger than $C$, so the best we can do is for one of them equal $C$ to cancel, and maximized the other (still cannot exceed $C$).  This happens when both $A$ and $B$ are equal to $C$, in which case the triangle is equilateral.