$(10$ pts $)$ Johnnie set a trip for the $610$ kg Wolf$-$Monster. A $40$ cm $-$wide Douglas Fir board juat spoans a

$9$ m wide ravine soch that when the wolf rackos ilbe position seen below, the slope at each end witt reach

$5$ degrees and both will fall. Determine the thickness$-$tb of the board by modelling the ends as simple

sapports. Note, include the weight of the beard in this calculation.