Ask your own question, for FREE!
Mathematics 11 Online
OpenStudy (anonymous):

IF YOU CAN HELP WITH EITHER ILL BE SO THANKFUL I HAVE A TEST TOMORROW a. The diagonals of a rectangle are 8 units long and intersect at a 60 degree angle. Find the dimensions of the rectangle. b. The perimeter of a rhombus is 64 and one of its angles has a measure of 120. Find the lengths of the diagonals

OpenStudy (jtvatsim):

I think the trick for the first one (a) is to use 30-60-90 triangles... but, have you learned that concept at any point in your course? :)

OpenStudy (jdoe0001):

that's better

OpenStudy (jdoe0001):

so can you tell what the width is?

OpenStudy (anonymous):

yes @jtvatsim but idk how to do this problem

OpenStudy (anonymous):

oh okay @jdoe0001 thanks

OpenStudy (jdoe0001):

|dw:1396224633566:dw| so the 2x side is 4, thus the "x" side will be half that

OpenStudy (jdoe0001):

ohh one sec... darn the hypotenuse is not 4... alright lemme do this

OpenStudy (jdoe0001):

\(\bf x\sqrt{3}={\color{blue}{ 4}}\implies x=\cfrac{{\color{blue}{ 4}}}{\sqrt{3}}\implies \cfrac{4\sqrt{3}}{3}\)

OpenStudy (jdoe0001):

you'd use also the 30-90-60 rule

OpenStudy (jdoe0001):

that'd be the rhombus so to find the diagonals length notice the right triangle, the blue lines are half of each diagonal so once you find those 2, the diagonals will be twice as much

OpenStudy (jdoe0001):

\(\bf 2x={\color{blue}{ 16}} \implies x=\cfrac{16}{2}\implies x={\color{red}{ 8}} \iff \textit{shorter side} \\ \quad \\ x\sqrt{3}\implies {\color{red}{ 8}}\sqrt{3} \iff \textit{longer side} \\ \quad \\ \quad \\ \textit{shorter diagonal}=2\cdot {\color{red}{ 8}}\implies 16 \\ \quad \\ \textit{longer diagonal}=2\cdot {\color{red}{ 8}}\sqrt{3}\implies 16\sqrt{3}\)

OpenStudy (anonymous):

@jim_thompson5910 can you try explaining the first one to me? i dont understand it

jimthompson5910 (jim_thompson5910):

This one? "a. The diagonals of a rectangle are 8 units long and intersect at a 60 degree angle. Find the dimensions of the rectangle. " or something else?

OpenStudy (anonymous):

yes that

OpenStudy (anonymous):

i think i got it idk if its right though

OpenStudy (anonymous):

i got the side across 90 degrees= 16 the side across 30 degrees= 8 radical 3/3 the side across 60 degrees=8

OpenStudy (anonymous):

@jim_thompson5910

jimthompson5910 (jim_thompson5910):

Ok let's start off with a drawing |dw:1396226868719:dw|

jimthompson5910 (jim_thompson5910):

One property you can prove about rectangles is that the diagonals are congruent. Another thing you can show is the diagonals cut each other in half. Because the diagonals are both 8 units, this means they cut each other into 4 unit pieces like this |dw:1396226991078:dw|

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!