Dr. J's Maths.com
Where the techniques of Maths
are explained in simple terms.

Trigonometric functions - Integration - Applications finding areas.
Test Yourself 1.


 

Solve the following problems as indicated:

Area -
1 curve
1. Find the area between y = 3sin 2x and the x-axis between x = 0 and
x = π.
Answer:Area = 6 u2.
2. (i) Sketch the curve y = 2cos 2x + 1 between x = 0 and x = π/2 showing the intercepts on the axes.

(ii) Find the exact area between the curve
y = 2cos 2x + 1 and the line y = 1
from x = 0 to x = π/3.

Answer:Area = 1.5 - π/4 u2.
  3. Find the area between the curve
y = 2sec2x and the x-axis between
x = 0 and x = π/4.
Answer:Area = 2 u2.
4. For the function f(x) = 2cos x + 1,

(i) State the range of f(x);

(ii) Sketch f(x) for 0 ≤ x ≤ 2π;

(iii) Calculate the exact area of the region bounded by the curve
y = 2cos x + 1, the y axis and the line y = 1.

  5. (i) Sketch the curve y = -1 - sin 3x
between x = 0 and x = π.

(ii) Find the area enclosed between the curve and the x axis between x = 0 and
x = π.

Answer:Area = π u2.
6. The diagram below shows the graph of
y = cos 2x + sin x.

Calculate the exact area between the curve and the x axis from x = -π/2 to π/2.

Answer:Area = (3√3)/2 u2.
  7. If f(x) = (1 + tan x)2 for .

(i) Solve f(x) = 0.

(ii) Find any stationary points on f(x) and determine their nature.

(iii) Sketch the graph of y = f(x).

(iv) Find the area bounded by the curve and the x-axis from

Answer:(i) At x = -π/4.
(ii) min TP at (-π/4, 0).
(iv) Area = 2 u2

8. The breathing cycle for an adult at rest takes 5 seconds on average.

For the first 2.5 seconds (0 < t ≤ 2.5), breath is taken into the lungs. For the remaining 2.5 seconds (2.5 < t ≤ 5), breath is exhaled.

The rate (R litres/second) at which breath is being inhaled into or exhaled from the lungs at time t through the 5 second cycle can be modelled by the equation

How many litres of air is inhaled into the lungs during one breathing cycle?

Area -
2 curves with no point of intersection.
9. (i) Sketch the graphs of y = sec2 x and y = x for 0 ≤ x ≤ π/4.

(ii) Find the area bounded by these curves, the y axis and the line x = π/4.

Answer:Area = 1 - π2/32.
10. (i) Sketch the graphs of x = sec2 x and y = cos x for [0 , π/2].

(ii) Find the area between the two curves within the domain [0, π/3].

Answer:Area = √3 /2 u2.
Area -
2 curves with one point of intersection
11. The diagram shows the curves .

(i) Show that the point of intersection has coordinates (1.5, 1).

(ii) Find the exact area described the the y axis and the area between the two curves up their point of intersection.

 

  12.

The diagram shows the region bounded by the curves y = sec2 x, y = 2 cot x and the coordinate axes.

(i) Show by substitution that the point lies on both y = sec2 x
and y = 2 cot x.

(ii) Differentiate ln (sin x).

(iii) Hence or otherwise, find the exact area of the shaded region.

Answer:(iii) Area = 1 + ln2 u2.
  13. (i) Sketch the graphs of y = sin 2x and y = 3 cos x in the domain 0 ≤ x ≤ π.

(ii) Find the area bounded between the two curves in the given domain.

Answer:Area = 4 u2.
 

14. (i) Sketch the curves y = sin 2x and y = cos x in the domain [-π/2, π/2].

(ii) fine the total area enclosed by these two curves in the given domain.

Answer:Area = 1.5 u2.
Area -
2 curves with two points of intersection
15.

The diagram above shows the graphs of y = sin x and y = √3 cos x (0 ≤ x ≤ 2π).

The graphs intersect at points A and B.

(i) Find the x coordinates of points A and B.

(ii) Find the area enclosed by the two graphs.

Answer:(iii) Area = 4 u2.
  16. (i) Show that the curves y = sec 2x - 1 and y = sin 2x intersect at x = 0 and
at x = 0.896 (correct to 3 decimal places). Draw a rough sketch if this helps.

(ii) Find the area between these two curves between the two points of intersection
(correct to 3 decimal places) .

Answer:(ii) Area = 0.397 u2.