Worked example 2 In the diagram, BC⊥AD, |∠BAC| = 39° , |AC| = 9 and |CD| = 13. (i) Calculate |BC| , correct to two decimal places. (ii) Hence, calculate |∠CDB| , correct to the nearest degree.
Strategy:
'We have … We have … We want …'
Solution (i)
We have: We have: We want:
A 39° 9 C 13
B
D
(ii)
We have: We have: We want:
Practice questions 19.4
1. Find the length of the labelled side in each triangle. Give your answers correct to one decimal place. (i)
(ii) 11 m 62° t 105 mm 61° x 18° (iv) 40° x 17.3 cm (v) a 64° 10.8 cm 20° p (vi) 3.5 m 60 m x (iii)