General Maths - HELP! with trig applications (1 Viewer)

[charlottejane]

i seriously:angry: need help with trig applications. if anyone could help with the following questions please do!

Im aware of basic trig (SOHCAHTOA) etc.
however i am in the unknown when it comes to Sin and Cos rules! I dont know when to use either? or how... if you could show me step by step working i would appreciate it immensly!
Questions are...

1. find the area of Triangle ABC, where a = 5, b = 7, C= 50. (1 dec pl.)

2. find the 3rd side of the triangle ABC, given a = 8, c = 12, b= 75degrees. (2 dec pl.)

3. hasam is a goal kicker in his rugby league team. hasam has a kick from the sideline to win a match. hasam is 39 metres from the near post and 45 metres from the far post. the goalmouth is 7m wide.
a) draw a diagram of this situation.
b) Calculate the angle within which hasam must kick in order to kick the goal.



any further information, possible step by step examples etc. of how and when to use sin and cos rules, pythagoras etc, would be life saving. thanks a million

 

[bling05]

1. Trig is not required, use pythag.
Formula for area of a triange is Base x Height/2
5 x 7/2 = 17.5

2. Use SOHCAHTOA.
In this case you could use Sin or Tan, however we will use Tan.
Tan 75 = b/8
Therefore b = Tan 75 x 8
b = 29.86

 

[Evan11]

Does C = 50 degrees or 50 units, cos unless its degrees i dont think this makes sense.

Also, is it assumed that this is a right angled triangle, because trig as you know it wont work unless it is.