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Mathematics 7 Online
OpenStudy (howard-wolowitz):

Medal for HELP :

OpenStudy (howard-wolowitz):

OpenStudy (anonymous):

The second question is it as two solutions.

OpenStudy (howard-wolowitz):

Hmm you think so

OpenStudy (anonymous):

yes, because it shows y=x-2 and -x+y=-5 and since there are two, there are two solutions.

OpenStudy (howard-wolowitz):

it could be one though

OpenStudy (anonymous):

since there are two equal signs it represents that there are two..that's what i recently learned.

OpenStudy (howard-wolowitz):

alright y can you help me with the first one

OpenStudy (anonymous):

I think it would be the first one

OpenStudy (howard-wolowitz):

I dont think hes right Michele

OpenStudy (howard-wolowitz):

but he might be with the first one

OpenStudy (michele_laino):

we can write this: \[a = c \times \cos B\]

OpenStudy (michele_laino):

so we have: \[\Large c = \frac{a}{{\cos B}} = \frac{a}{{\sqrt {1 - {{\left( {\sin B} \right)}^2}} }} = ...?\]

OpenStudy (michele_laino):

substituting our data, we get: \[\Large c = \frac{a}{{\cos B}} = \frac{a}{{\sqrt {1 - {{\left( {\sin B} \right)}^2}} }} = \frac{{20}}{{\frac{{\sqrt 3 }}{2}}} = \frac{{40}}{{\sqrt 3 }}\]

OpenStudy (michele_laino):

now we have to rationalize. Please multiply both numerator and denominator by sqrt(3), what do you get?

OpenStudy (howard-wolowitz):

I got 360

OpenStudy (howard-wolowitz):

which cant be right

OpenStudy (michele_laino):

second question: If I substitute the first equation into the second one, I get: -x+x-2=-5 please simplify that expression

OpenStudy (howard-wolowitz):

you get no solution

OpenStudy (howard-wolowitz):

For the first one though I got 40

OpenStudy (michele_laino):

first question: \[c = \frac{a}{{\cos B}} = \frac{a}{{\sqrt {1 - {{\left( {\sin B} \right)}^2}} }} = \frac{{20}}{{\frac{{\sqrt 3 }}{2}}} = \frac{{40}}{{\sqrt 3 }} = \frac{{40\sqrt 3 }}{{\sqrt 3 \times \sqrt 3 }} = ...?\]

OpenStudy (michele_laino):

\[\large c = \frac{a}{{\cos B}} = \frac{a}{{\sqrt {1 - {{\left( {\sin B} \right)}^2}} }} = \frac{{20}}{{\frac{{\sqrt 3 }}{2}}} = \frac{{40}}{{\sqrt 3 }} = \frac{{40\sqrt 3 }}{{\sqrt 3 \times \sqrt 3 }} = ...?\]

OpenStudy (howard-wolowitz):

I get |dw:1431978216548:dw| because i combined them

OpenStudy (michele_laino):

that's right!

OpenStudy (howard-wolowitz):

sweet

OpenStudy (michele_laino):

hint: second question, after a simplification we have: -2=-5

OpenStudy (howard-wolowitz):

well then two solutions then -2=-5

OpenStudy (michele_laino):

no, it is not an equation, since the statement -2=-5 is false, so we have no solutions

OpenStudy (howard-wolowitz):

oh I thought you meant i was wrong... sorry my bad

OpenStudy (howard-wolowitz):

Thank you for explaining those to me!

OpenStudy (michele_laino):

Thank you!

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