Why is 0.384 lighter then 0.3798

What is the standard form of -5x^2+2x^4-11+x^3+3x

1. 2. ∠b and ∠y are right angles. 3.? 4.? which two statements are missing in steps 3 and 4? ∠x ≅ ∠c △abc ~ △zyx by the sas similarity theorem. ∠b ≅ ∠y △abc ~ △zyx by the sas similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem.

If cos(θ)=2853 with θin q iv, what is sin(θ)?