Trigonometric Problems

1)
cos角ICB=BC/IC
cos角ICB=20/40=1/2
角ICB=60度

2)
sin角HEJ=HJ/HE
sin角HEJ=HJ/40
HJ=40sin角HEJ

3)
KL=HJ=40sin角HEJ
tan角ICB=KL/LC
tan60度=40sin角HEJ/LC
開方3=40sin角HEJ/LC
LC=40sin角HEJ/開方3
BL=BC-LC
BL=20-(40sin角HEJ/開方3)

4)
角HKC=角LCK(錯角,KH//LJ)=60度
將CD水平推,直到D,H點重疊,得出新線HC'
sin角HKC'=HC/HK
sin角HKC'=20/HK
sin角60=20/HK
HK=20/sin角60
HK=40/開方3

are u having exam tmr???

F.3 Question.
can't use Law of Cosines.

Are we allowed to use the Law of Cosines?

(Forgive this question as we can't calculate anything without using the LoC)