since it's pinned at A and C, it is statically determinate.
Consider the applied load creates a moment at A, but A is pinned. So BC reacts the moment at A, and A reacts the nett vertical load (applied-BC component) and the horizontal component of BC.
So the horizontal couple between A and C reacts the applied moment at A. MA = 3*3*1.5, and AC = 1.5, so the horizontal couple is 9kN.
Then the vertical component of BC is 9*1.5/2, and the vertical component at A is 9 (applied)-9*1.5/2 = 9/4.
See if this makes sense, show us your work, then we can help you understand it.
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General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.