Cos(A-B) = cosAcosB + sinAsinB
<span>
cos(</span>π/2 - θ) = cos(π/2)cosθ + sin(π/2)sinθ
π/2 = 90°
cos(π/2) = cos90° = 0. sin(π/2) = sin90° = 1
cos(π/2 - θ) = cos(π/2)cosθ + sin(π/2)sin<span>θ
</span>
= 0*cosθ + 1*sin<span>θ = </span>sin<span>θ
Therefore </span>cos(π/2 - θ) = sin<span>θ
QED </span>
90 × 7 = 630 , it's not hard, it's easy
Just add them
QM+MR=QR
16+x+2(x+2)=QR
16+x+2x+4=QR
20+3x=QR
Answer:
28 questions answered.
Step-by-step explanation:
40(2/5) is 16 questions.
40-16 is 24 questions left.
24(.5) is 12 questions.
16+12 gets you 28 questions.
True the variable in the expression is y
