Sine Cosine and Tangent Ratios

Use similarity to investigate the constancy of the sine, cosine and tangent ratios for a given angle in right-angled triangles (ACMMG223)

Apply trigonometry to solve right-angled triangle problems (ACMMG224)

LO:To investigate Sine, Cosine and Tangent ratios and use trigonometry to solve right-angled triangle problems.

Know:

  • the properties of right-angled triangles.

Understand:

  • That there is a link between the sine, cosine and tangent ratios in right-angled triangles

Do:

  • I can use the sine, cosine and tangent ratios.

Properties of Right-Angled Triangles

“Opposite” is the opposite to the angle.
“Adjacent” is next to the angle.
“Hypotenuse” is the long side of the right-angled triangle and is always opposite of the right angle.

There are 3 ratios to help identify the length of the sides.

sin angle = opposite side / hypotenuse

cos angle = adjacent side / hypotenuse

tan angle = opposite side / adjacent side

Teaching Ideas

Trigonometry Videos

BBC Trigonometry
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