Im not in geometry class but i can say its B
DC/AC=EC/BC
x/(x+3)=10/16
10(x+3)=16x
10x+30=16x
30=6x
x=5
DC=x=5
DC=5 units long
10/16=DE/AB, DE=y
10/16=y/10
16*y=10*10
y=6.25≈6.3
DE≈6.3
Answer:
Step-by-step explanation:
Don't use 0 as a substitute for θ. 0 is always 0.
cosθ = -5/(2√15)
secθ = 1/cosθ = -2√15/5
