Problem $4-6$a

The link lengths $(a,b,c,d)$ and the value of ${}_2$ for a crank$-$rocker linkage are defined as

$2,7,9,6,30,$ respectively. Draw the scaled linkage. Find all possible solutions $($both

open and crossed$)$ for angles ${}_3$ and ${}_4$ graphically.

$($This is not the scaled kinematic diagram.$)$