Here is an assortment of problems from Math 8, Math 10 and Math 30, where multiple concepts are a part of each problem, or used in the solution. Clearly, algebra plays a large part in solving most problems, but sometimes the solutions can be a little unusual when you are dealing with, for example, trigonometry and logarithms in the same problem!


Problem 1: Math 8    [geometry + algebra]

Find θ

Solution:
The two angles on the right of the transversal are supplementary:
2x - 40  +  x + 70 = 180°
3x + 30 = 180
3x = 150
x = 50    This makes angle 2x - 40 equal to 2(50) - 40 = 60°
The supplementary angle θ = 120°



Problem 2: Math 10    [measurement formulas + algebra]

Find the area of the circle

Solution:
Area = πr2
The radius is 2x + 6
A = π(2x + 6)2
A = π(4x2 + 24x + 36)



Problem 3: Math 30    [logarithms + trigonometry]

Solve for θ   if  0 < θ < π/2:





Problem 4: Math 30    [factoring + trigonometric identities]

Simplify:

    sin4θ - cos4θ
     (sinθ - cosθ)

= (sin2θ + cos2θ)(sin2θ - cos2θ)
          (sinθ - cosθ)

= 1·(sin2θ - cos2θ)
      (sinθ - cosθ)

= (sinθ + cosθ)(sinθ - cosθ)
           (sinθ - cosθ)

= sinθ + cosθ



Problem 5: Math 30    [algebra + quadratic equations + logarithms]

Solve:

2log2x - log2(x + 3) = 2
log2x2 - log2(x + 3) = 2

log2    x2      =  2
       (x + 3)

22 =   x2   
      (x + 3)

4 =   x2   
      (x + 3)

4x + 12 = x2
x2 - 4x - 12 = 0
(x - 6)(x + 2) = 0
x = 6  or  x = -2
x = -2 gives a log of a negative, so the only answer is x = 6


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