$R_x = \Sigma F_x$
$R_x = 10\,000 - 6000 \sin 60^\circ$
$R_x = 4803.85 \, \text{ lb to the right}$
$R_y = \Sigma F_y$
$R_y = 24\,000 + 6000 \cos 60^\circ$
$R_y = 27\,000 \, \text{ lb downward}$
$R = \sqrt{{R_x}^2 + {R_y}^2}$
$R = \sqrt{4803.85^2 + 27\,000^2}$
$R = 27\,424.02 \, \text{ lb}$
$\tan \theta_x = \dfrac{R_y}{R_x}$
$\tan \theta_x = \dfrac{27\,000}{4803.85}$
$\theta_x = 79.91^\circ$
Righting moment
$RM = 24\,000(18 - 7) + 6000(4)$
$RM = 288\,000 \, \text{ lb}\cdot\text{ft}$
Overturning moment
$OM = 10\,000(6)$
$OM = 60\,000 \, \text{ lb}\cdot\text{ft}$
Moment at the toe (downstream side - point B)
$M_B = RM - OM$
$M_B = 288\,000 - 60\,000$
$M_B = 228\,000 \, \text{ lb}\cdot\text{ft counterclockwise}$
Location of Ry as measured from the toe
$R_yx = M_B$
$27\,000x = 228\,000$
$x = 8.44 \, \text{ ft to the left of B}$ (within the middle third)
Thus, R = 27 424.02 lb downward to the right at θx = 79.91° and passes through the base at 8.44 ft to the left of B which is within the middle third.
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