The sides of right-angled triangles are labelled opposite, hypotenuse and adjacent. Trigonometry explores the relationship between sides and angles in right-angled triangles. The hypotenuse is the ...

Luckily, triangles survived nonetheless—and thrived. In “Love Triangle: How Trigonometry Shapes the World,” Matt Parker recounts, for instance, how computers were a “game-changer in the ...

Trigonometry ... in a right-angled triangle when another side and an angle are known. An understanding of the three trigonometric ratios and how to change the subject of a formula is essential.

So we've reduced the question to showing that sin(54°) = φ/2. The trick now is to consider the isosceles triangle ABC shown below, whose angles are 36°, 72° and 72°.

But do you really understand the very basic concepts of trig? Yes, I just call it "trig" because I always misspell trigonometry. Maybe you can use the double angle formula and you don't have a ...