Could sum1 please help me with these two questions. (1 Viewer)

[chooky_girl26]

Could someone please explain these two questions to me as i don't understand one of the questions and i don't understand how to find diagonal length.

Opps three questions sorry

The sides of a parallelogram are 5.3cm and 11.3cm. The sides meet at angles of a34 degrees and 46 degrease.
a. Draw a diagram of the parallelogram showing this information and mark both diagonals on it.- i can do this bit
b. Calculate the length of the shorter diagonal correct to 1 dp
c. Calculate the length of the long diagonal correct to 1 dp.

I do not know how to do parts b and c of this question.

The second question is....
The cord supporting a picture frame is 58cm long. It is hung over a single hook in the centre of the cord and the cord then makes an angle of 145 dg . Calculate the length of the backing of the picture frame to the nearest centimetre.


Ok the last question i do not understand how to do is this...
A soccor goal is 8 m wide
a. A player is directly in front of the goal such that he is 12m from each post. Within what angle must he kick the ball to score a goal?
b. A second player takes an angled shot. This player is 12 m from the nearest post and 17 m from the far post. Within what angle must this player kick to score a goal.

Could someone please help me with these three questions. All have something to do with the cosine rule.
I do not understand how to work them out. Would be much appreciated if someone could help
Thank you very much
Alysha
xooxoox
P.S THANK U

 

[PC]

The Cosine Rule

Hey Chooky!

Have a look at my attachment for answers to your questions.

The cosine rule isn't too hard to learn. Draw a triangle and pick an angle, and mark it in some way. Then mark the two sides ADJACENT to this angle. So you've got three things marked: two sides and the angle in between them. This is what you need to use the cosine rule to find a side.

So ... to find the third side the rule says "third side SQUARED equals first side squared plus second side squared MINUS two times first times second times cos of the angle between them" ... and then just remember to take the square root. That's it.

If you need to find an angle (like in your third question) you will need all sides of the triangle. The angle you are trying to find will have an opposite side, and there will be two adjacent sides. In this case "cos of angle equals first side squared plus second side square MINUS OPPOSITE side squared all over two times first times second" ... then just remember that this is the cos of the angle, not the actual angle. Press [SHIFT][COS][SHIFT][Ans] or something else depending on your calculator to get your answer.

Hope this helps!

 

[chooky_girl26]

Wow thanks

Wow thank PC thanks a lot.... those questions puzzled me... thanks for helping... i really appreciate it.
Love Lysha
xoxox