An introduction to Trigonometry A

A Opposite

An introduction to Trigonometry A Opposite Hypotenuse

An introduction to Trigonometry A Opposite Hypotenuse Adjacent

Example Label each of the following triangles (i)(ii)(iii) a c b f g ih e d

Example For the triangle below a)Write down the lengths of the opposite and hypotenuse sides b)Work out the ratio 8cm 41.8° 12cm c) Now work out the sin of 42° using the calculator Opposite = 8cm Hypotenuse = 12cm Sin 41.8°=0.6665

Right-angled Trigonometry A Opp Hyp Adj

Example Work out the lettered length in the triangle given below, giving your answer to 1 decimal place. a 25° 8 cm

Example Work out the lettered length in the triangle given below, giving your answer to 1 decimal place. b 15 m 48°

Example Work out the lettered length in the triangle given below, giving your answer to 2 decimal place. b 37 cm 15°

Example Work out the length of AB in the triangle given below, giving your answer to 2 decimal place. A 7 m C B 56°

Example For the triangle below a)Write down the lengths of the Adjacent and hypotenuse sides b)Work out the ratio 7cm 54.3° 12cm c) Now work out the cos of 54.3° using the calculator Adjacent = 7cm Hypotenuse = 12cm cos 54.3°=0.5835

Right-angled Trigonometry A Opp Hyp Adj

Example Work out the lettered length in the triangle given below, giving your answer to 1 decimal place. a 31° 10 cm

Example Calculate the length of PQ in the triangle PQR 32  52 cm Q R P

Example Calculate the length XY in the triangle XYZ 59  4.6 cm Z X Y

Right-angled Trigonometry A Opp Hyp Adj

Example Work out the lettered length in the triangle given below, giving your answer to 1 decimal place. a 27° 4 cm

Example Calculate the length YZ in the triangle XYZ, giving your answer correct to 3 significant figures. 38  4.6 cm Z X Y

Example Work out the length of AC in the triangle given below, giving your answer to 2 decimal place. A 7 m C B 56°