Quick Answer: Trigonometry examples show how to use sin, cos and tan to find heights, distances and angles. A 60 m kite string at 30 degrees gives a height of 30 m, and a 24 m tower with a 24 m shadow means a 45 degree sun angle.
Key takeaways:
- Follow draw, label, pick ratio, solve.
- Angle of depression equals angle of elevation from the other end.
- The 3-4-5 triangle gives a 36.87 degree angle.
- Use identities to simplify proofs.
- Check answers with Pythagoras or a calculator.
Reading about trigonometry helps, but solving a few problems is what makes it stick. This page collects beginner-friendly examples, each with a diagram description, a step-by-step solution and a check. The situations are familiar ones from Indian schools and sites: a kite string, a bridge ramp, a mobile tower, a staircase. You can verify your answers with the free trigonometry calculator.
Key takeaway: Every example follows the same four moves: draw, label, pick the ratio, solve. If you keep to that routine, any new problem will feel familiar.
Example 1: Kite String
A kite flies at the end of a 60 m string, and the string makes a 30 degree angle with the ground. Assume the string is straight. The height of the kite is the opposite side and the string is the hypotenuse, so sin 30 = h / 60. h = 60 x 0.5 = 30 m. The horizontal distance is 60 x cos 30 = 51.96 m. Check: 30 squared plus 51.96 squared is 3,600, the square of 60.
Example 2: A Mobile Tower Shadow
At noon, a 24 m tower casts a shadow of 24 m. What is the sun’s angle of elevation? tan theta = 24 / 24 = 1, so theta = 45 degrees. If the shadow lengthens to 41.57 m later in the day, tan theta = 24 / 41.57 = 0.5774, so theta = 30 degrees.
Example 3: Staircase Design
A staircase in a house must climb 3 m over a horizontal length of 4 m. The angle is arctan(3 / 4) = 36.87 degrees, and the slope length (stringer) is 5 m by the 3-4-5 triangle. Each step has a rise of 17 cm, so the number of steps is about 3,000 / 170 = 17.6, which a designer would round to 18 steps of about 16.7 cm. Staircase codes limit rise and tread for safety, so always check local building rules or the National Building Code for the permitted limits.
Example 4: Angle of Depression from a Balcony
From a balcony 12 m above the ground, a person sees a parked scooter at an angle of depression of 40 degrees. How far is it from the building? The angle of depression equals the angle of elevation from the scooter, so tan 40 = 12 / d. d = 12 / 0.8391 = 14.3 m.
Example 5: Bridge Cable Angle
A cable on a small footbridge connects the top of a 6 m pillar to a point on the deck 8 m away. Length = sqrt(6 squared + 8 squared) = 10 m. Angle with the deck = arctan(6 / 8) = 36.87 degrees. Again a 3-4-5 style triangle, scaled up by two.
Example 6: Two Observers
Two friends stand on opposite sides of a 30 m high water tank. They see the top at elevations of 30 degrees and 60 degrees. How far apart are they? Distance of the first = 30 / tan 30 = 30 / 0.5774 = 51.96 m. Distance of the second = 30 / tan 60 = 30 / 1.7321 = 17.32 m. Total = 69.28 m. This type of question appears often in Class 10 board papers.
Example 7: Identity Check
Prove that (1 – sin squared A) x sec squared A = 1. Since 1 – sin squared A = cos squared A, the expression becomes cos squared A x (1 / cos squared A) = 1. This short route is typical of identity problems: rewrite using a basic identity and cancel.
Standard Values for Quick Practice
| Angle | sin | cos | tan |
|---|---|---|---|
| 30 degrees | 1/2 | sqrt(3)/2 | 1/sqrt(3) |
| 45 degrees | 1/sqrt(2) | 1/sqrt(2) | 1 |
| 60 degrees | sqrt(3)/2 | 1/2 | sqrt(3) |
Practice Set with Answers
- A 10 m ladder reaches 8 m up a wall. Find the angle with the ground. (Answer: arcsin 0.8 = 53.13 degrees.)
- A pole casts a 10 m shadow when the sun is at 60 degrees elevation. Find its height. (Answer: 10 x 1.7321 = 17.32 m.)
- Find sin 60 x cos 30 + cos 60 x sin 30. (Answer: sin 90 = 1.)
- A road rises 5 m over 100 m horizontally. Find the angle. (Answer: arctan 0.05 = 2.86 degrees.)
Benefits of Learning Through Examples
Real situations show why trigonometry matters. A kite, a tank and a staircase are things you can picture, and picturing helps memory. Repeating the draw, label, pick and solve routine builds speed. Examples also show how exam questions are framed, which lowers anxiety about word problems.
Challenges and Limitations
Examples simplify real life. Real strings sag, ground can slope, and measuring angles by hand has errors of a degree or more. In practice, engineers repeat measurements and use instruments such as theodolites or total stations, which are common in Indian survey work. Treat the examples as training for the method.
Common Mistakes in Beginner Problems
- Using the hypotenuse as adjacent. Label sides carefully.
- Mixing angle of elevation and the complementary angle. Measure from the horizontal.
- Not converting units. Keep metres with metres.
- Dropping the observer’s height when the question includes it.
- Using a calculator in radian mode for a degree question.
Best Practices
- Write given and to find at the top of every solution.
- Solve symbolically first, then plug in numbers.
- Check with Pythagoras once you have two sides.
- Review mistakes in an error notebook.
- Use the sine calculator for quick value checks.
Conclusion
These seven examples and the practice set cover the heart of beginner trigonometry: heights, distances, slopes and identities. Return to them whenever a new problem looks strange, follow the four-move routine and check your final numbers with a calculator. Consistent practice will turn trigonometry from a worry into a skill.
How to Create Your Own Examples
Once you have worked through the problems above, make your own. Look around your home or school and pick something tall or sloping: a water tank, a gate, a ramp, a tree. Pace out a known distance on level ground, estimate the angle to the top using a simple protractor with a string and a weight, and then calculate the height. Compare with a rough guess or a known value, such as the floor height of a building. This hands-on exercise often teaches more than ten textbook questions, and it shows how the same ratios work in a real setting.
What Examiners Look For
In board exams, marks are given for method as well as for the final answer. A neat diagram with labelled sides, a clear statement of the ratio used, the substituted values and the final answer with units can earn most of the credit even if there is a small arithmetic slip. Writing the standard values you used, for example tan 60 degrees = sqrt(3), makes your working easy to follow. Practising this layout with the examples above will help you present answers clearly under time pressure.
Try Changing the Numbers
A good way to learn from any example is to change one number and predict the result before you calculate. In the kite problem, what happens if the string makes 45 degrees instead of 30? The height should rise, because the string points more steeply upward. Calculate 60 x sin 45 = 42.4 m and see whether your guess was right. In the staircase example, what happens if the horizontal length grows from 4 m to 5 m while the rise stays 3 m? The angle falls to arctan(0.6) = 30.96 degrees, a gentler and more comfortable climb. Such small experiments turn formulas into intuition.
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FAQs
What is an easy trigonometry example?
A kite string of 60 m at 30 degrees to the ground reaches a height of 60 x sin 30, which is 30 m. This uses the sine ratio with the string as hypotenuse.
How do I solve angle of elevation problems?
Draw the horizontal line from the observer, mark the angle up to the object, and use tan if you know the distance and want the height. Height equals distance times tan of the angle.
What is the difference between angle of elevation and depression?
Elevation is measured upward from the horizontal, depression downward. The two are equal when taken between the same two points because they are alternate angles.
Do trigonometry examples need a calculator?
Not for standard angles like 30, 45 and 60 degrees, whose values you can memorise. Other angles need a calculator or table.
Where can I get more practice?
Start with NCERT Class 10 Chapters 8 and 9 and their exemplar problems, then try previous-year board papers. Check your answers with the free trigonometry calculator.