Find $(to$ the nearest degree$)$ the three angles $of$ the triangle with vertices $at$

$A(2,-7,3),B(-1,5,8),$ and $C(4,6,-1).$

Find the vector $pro{j}_{a}bifa=2i+j+2k$ and $b=3j+4k.$

Find the angles between the curves $y=1-x^2$ and $y=x^2-1at$ their points $of$

intersection $(there$ are $2$ points, $so$ there will $be4$ angles$).$ Remember that the

angles between two differentiable curves $at$ a point $of$ intersection are the angles

between the curves' tangent lines $at$ these points.

Find the work $W$ done $by$ the force $F=i+3j-kin$ moving the particle $ona$

straight line from $P(0,0,0)toQ(3,1,0).$

Find two different unit vectors $u$ and $v$ both $of$ which are perpendicular $to$ the given

vectors $a=4i-2j$ and $b=j-2k.$

Find the area $of$ the triangle with vertices $P(2,-7,3),Q(-1,5,8),$ and $R(4,6,-1).$