In these lessons, examples, and solutions we will learn the trigonometric functions (sine,
cosine, tangent) and how to solve word problems using trigonometry.
More Lessons on Trigonometry
The following diagram shows how SOHCAHTOA can help you remember how to use sine, cosine, or tangent to find missing angles or missing sides in a trigonometry problem. Scroll down the page for examples and solutions.
How to solve trigonometry problems or questions?
Step 1: If no diagram is given, draw one yourself.
Step 2: Mark the right angles in the diagram.
Step 3: Show the sizes of the other angles and the lengths of any
lines that are known.
Step 4: Mark the angles or sides you have to calculate.
Step 5: Consider whether you need to create right triangles by
drawing extra lines. For example, divide an isosceles triangle
into two congruent right triangles.
Step 6: Decide whether you will need the Pythagorean theorem, sine, cosine
Step 7: Check that your answer is reasonable. The hypotenuse is the
longest side in a right triangle.
How to use Cosine to calculate the side of a right triangle?
Calculate the value of cosθ in the following
Use the Pythagorean theorem to evaluate the length of PR.
How to use Tangent to calculate the side of a triangle?
Calculate the length of the side x, given that tan
θ = 0.4
How to use Sine to calculate the side of a triangle?
Calculate the length of the side x, given that sin
θ = 0.6
Using the Pythagorean theorem:
How to solve Word Problems using Trigonometry?
Example: The following video shows how to use the trigonometric ratio, tangent, to find the height of a balloon.
How to solve Word Problems using Sine?
This video shows how to use the trigonometric ratio, sine, to find the elevation
gain of a hiker going up a slope.
Example: A hiker is hiking up a 12 degrees slope. If he hikes at a constant rate of 3 mph, how
much altitude does he gain in 5 hours of hiking?
How to Use Cosine to Solve a Word Problem?
Example: A ramp is pulled out of the back of truck. There is a 38 degrees angle between the ramp
and the pavement. If the distance from the end of the ramp to to the back of the truck
is 10 feet. How long is the ramp?
Step 1: Find the values of the givens.
Step 2: Substitute the values into the cosine ratio.
Step 3: Solve for the missing side.
Step 4: Write the units
How to solve Word Problems using Tangent?
The following video shows how to use trigonometric ratio, tangent, to find the height of a building
How to solve trigonometry word problems using tangent?
Example: Neil sees a rocket at an angle of elevation of 11 degrees. If Neil
is located at 5 miles from the rocket launch pad, how high is the
How to determining the speed of a boat using trigonometry?
Example: A balloon is hovering 800 ft above a lake. The balloon is observed
by the crew of a boat as they look upwards at an angle of 0f 20
degrees. 25 seconds later, the crew had to look at an angle of 65
degrees to see the balloon. How fast was the boat traveling?
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