Trigonometri

AD=k AC=5k DC=BC=4k
AB=3k
m(DBC)=Q
cot(180-2Q)=-cot2Q=4/3
cot2Q=-4/3
1-cot²Q/2QcotQ=-4/3
3-3cot²Q=-8cotQ
3cot²Q-8cotQ-3=0
3cotQ +1
cotQ -3
cotQ=-1/3 cotQ=3
cot 0 ile 90 derece arasinda oldugu icin
cotQ=1/3
Cevap B