3 The area of a triangle is \( 10 \mathrm{~cm}^{2} \). If the base of the triangle were increased by \( 10 \% \) and the height of the triangle were decreased by \( 10 \% \), what would be the area of the new resulting triangle?

8. Find the volume of the box (parallelepiped) determined by the points \( P=(1,2,4) \), \( Q=(2,-5,8), R=(4,2,-3) \) and \( S=(3,5,-6) \). 9. Find the volume of the box (parallelepiped) determined by the points \( P=(8,5,3) \), \( Q=(4,6,7), R=(-4,-2,9) \) and \( S=(3,-3,-4) \).

1. If a rectangle has a length of 10 m and a height of 5 m , what is its perimeter?

Figure 4.27 The areas of two similar triangles are \( 64 \mathrm{~cm}^{2} \) and \( 144 \mathrm{~cm}^{2} \), a) Find the ratio of their altitudes. b) If the perimeter of the smaller triangle is 49 cm , find the perimeter of the larger triangle.

3. Find a vector perpendicular to the plane of using the points \( P=(1,2,-4) \), \( Q=(2,5,-7) \) and \( R=(3,-5,-1) \). Also find area of the parallelogram and area of triangle. Furthermore find a unit vector perpendicular to the plane using these points.

If two vertically opposite angles are supplementary, then the measure of each angle of them equals \( \begin{array}{llll}\text { (a) } 45^{\circ} & \text { (b) } 60^{\circ} & \text { (c) } 90^{\circ} & \sqrt{3}\end{array} \)