Maths- sine and cosine rule questions?

Question

my triangle looks like this abit

.........................*...............

.......................*....*............

...10.3 cm......*.........* x cm...................

...................*..............*......

..................*..a............b..*...

................*...*....*....*...*......

a=58degrees

b=37degrees

now the question says: determine x in each of the following giving your answer correct to one decimal place and showing clearly how the sine or cosine rule is used in each case.

i have no idea how to do these questions if you could help it would be great. thanxx also ignore the dots, it dosent mean anything.

Answer 1

lets see if i can remember...

i know this for a fact...

sin= opposite/hyp

cos=adj/hyp

tan=opp/adj

but iunno how to figure it out if its not a right triangle... hmm

well i hope the info i gave you helps at all...

it might be diff tho

its been awhile for me  

Answer 2

Thank god, 2d...

Alright well lets see you want to find x using sin/cos rules. Well first of all lets solve for the remaining angle using the fact that the angles of a triangle alway add up to 180, making that remaining blank angle 85, lets call it angle c cause its a pretty name. Now then lets use the sine rules since its the only one i can remember at the moment, basically it states:

Sin A/a = Sin B/b = Sin C/b

where A,B,and C are our angles and a,b, and c are our side lengths.

Now just so ya know the side length across from an angle shares that letter. So that makes x side length a since its across from angle A. It also makes that 10.3cm side length b and that 37 degrees angle B.

This is nice since it lets us use that sine law thingy to solve the problem. We really only need to use this part:

SinA /a = SinB /b

lets see A = 58degrees, a = x, B = 37 degrees, and b = 10.3cm

Plug and chug ftw, (make sure your calcs in degree mode)

Sin (58) /x = Sin (37)/10.3

Sin(58)/x = .058428643

multiply both sides by x

sin(58) = .058428643x

.8480480962 = .05842864x

simple algebra...

x = 14.51cm approximately.

Well there ya go.

lolz and those other retards thought u meant the sohcahtoa rules...

O and also could you maybe next time ask this on student of fortune so I can make a quick buck?

Answer 3

it's been awhiles since i did trig, but the rule is somethign like  sina/sidea = sinb/sideb? i think, so you basically just find sine of 37degress divide by 10.3 and get a decimal(you constant i guess you could say).  Thent ake the sin of A and multiply that by your constant? I think.