The slope distance and zenith angle between points A and $B$ were observed with a total station

instrument as having a value of $8500\mathrm{.}15$ m and an angle of $82{19}^{\text{'}}{44}^{\text{'}\text{'}},$ respectively. The hi and

rod reading $r$ are equal. If the elevation of $B$ is $12800\mathrm{.}91$ m $,$ what is the elevation of $A?$ Show

answers with two decimal digits. Draw the diagram labeling $hi,r,V,$ delta elev, $H,S,$ the rod and

the total station instrument.