In ΔQRS, the measure of ∠S=90°, the measure of ∠Q=54°, and RS = 26 feet. Find the length of QR to the nearest tenth of a foot

SOH-CAH-TOA

sin Q     =    Opposite     =    26

                 hypotenuse          x

sin 54   =     26

                     x

x sin 54 = 26

x sin 54      =         26    

sin 54                sin 54

x =        26      =    32.1378  ≈  32.1 feet

          sin 54

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12