Examples

1a) Find the missing angles & state why:













1 58 F-rule 
2 24 Z-rule
3 98 Angle sum of a triangle is 180°
4 58 Equal angles as a result of an isosceles triangle
5 64 Angle sum of a triangle is 180°
6 64 Angle sum of a triangle is 180°
7 64 Z-rule
8 71 Angle sum of a triangle is 180°
9 109 C-rule


b)

 












1 45° C-rule
2 100° X-rule
3 35° Angle sum of a triangle is 180°
4 35° C-rule
5 35° Z-rule
6 35° Z-rule
7 80° X-rule


2) Given two similar triangles, all corresponding sides are equally proportional.
Solve for M and N:


M = 14            
                       
N = 8              







20 / 10 = 2
7 x 2 = 14
16 / 2 = 8

3a) Solve the missing angles:


1 26°
2 72°
3 53°
4 53°
5 214°






b)
1 94°
2 94°
3 86°
4 45°







4) A hemispherical pot is used for a hanging basket. The width of the surface of the soil is 30cm. The maximum depth of the soil is 10cm. Fine the radius of the pot:
1) x² = (x-10)²  + 15²

2) x²  = x²  - 20x + 100 + 25

3) 20x = 325
4) ----     -----
     20       20
5) x = 16.25


 
The radius of the pot is 16.25cm.


5) A water sprinkler turns back and forth through an angle of 100° . The water sprays out to a maximum distance of 25m.

A) What is the length of the arc of the watered sector, to the nearest metre?

The Length, l, of and arc with a central angle of m° is given my the formula:
             1) l = m
                     ---  x 2πr
                    360
             
             2) l = 100
                       -----  x 2π x 25
                       360

             3) l = 44 m°



B) What is the area of the watered sector, to the nearest square metre?

The area, A, of a sector with a central angle of m° is given by the formula:


              1) A = m°
                     -----  x π
                      360

              2) A = 100
                         -----  x π x 25²
                         360

              3) A = 545 m²