Trigonometry: Sine, Cosine, Tangent
Learn the basic trigonometry ratios and how to use them to find missing sides or angles in right-angled triangles. Let's get started! 🚀

Video Lesson
Watch and learn the basics

Flashcards
Review key concepts visually
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🛎️ What Are sin, cos, and tan?
- These are ratios used in right-angled triangles
- Once the angle is given, the ratios are fixed
🛎️ Using sin, cos, and tan
- SOH:
- CAH:
- TOA:
🛎️ Finding a Missing Side
- Choose sin, cos, or tan based on the sides you know and the side you want
- Substitute the values and rearrange to find the unknown side
🛎️ Finding a Missing Angle
- Write the correct trig ratio first (sin, cos, or tan)
- Use the inverse function on the calculator (, , or )
🛎️ Common Trigonometric Values
- You should know the exact values for 30°, 45°, and 60° without a calculator
- Having these triangles in your head helps you see the ratios instantly
Practice Questions
Test your understanding
In a right-angled triangle, the opposite side is , and the hypotenuse is . What is the sine of the angle?

Correct! 🎉 +10 pointsNot quite right
The sine formula is . Here, the opposite side is and the hypotenuse is . So, the sine of the angle is .
In a right-angled triangle, the adjacent side is , and the hypotenuse is . What is the cosine of the angle?

Correct! 🎉 +10 pointsNot quite right
The cosine formula is . Here, the adjacent side is and the hypotenuse is . So, the cosine of the angle is .
What is the sine of the angle?

Correct! 🎉 +20 pointsNot quite right
The sine formula is . Here, the opposite side is and the hypotenuse is . So, the sine of the angle is .
What is the tangent of the angle?

Correct! 🎉 +20 pointsNot quite right
Using the tangent formula , here the opposite side is and the adjacent side is . So, the tangent of the angle is .
What is the cosine of the angle?

Correct! 🎉 +20 pointsNot quite right
Using the cosine formula , here the adjacent side is and the hypotenuse is . So, the cosine of the angle is .
Find the angle in the right-angled triangle.

Correct! 🎉 +30 pointsNot quite right
The sine formula is . Here, the opposite side is and the hypotenuse is , so . Using the inverse sine function, .
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Interactive Activity
Explore trigonometric ratios in a right triangle
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