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Mathematics 20 Online
zarkam21:

Help

zarkam21:

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Vocaloid:

well you have two angles A and C, how would you find the missing angle B?

zarkam21:

law of sines

Vocaloid:

remember, when you have two angles in a triangle, 180 - angle - other angle = will give you the missing angle

zarkam21:

oh okay so 180-42-83=55

Vocaloid:

yup then for part II) you can use a/sinA = b/sinB to find a

zarkam21:

a/sinA = b/sinB 175/42=b/83

zarkam21:

2075/6

Vocaloid:

check again, angle B is not 83 degrees

Vocaloid:

also you need to include sin in the denominators

zarkam21:

a/sinA = b/sinB 175/sin42=b/sin55 b=214.24

Vocaloid:

175 is side b not a we are solving for side a

Vocaloid:

a/sin(42) = 175/sin(55)

zarkam21:

142.95

Vocaloid:

A+

Vocaloid:

oh right I forgot it's asking for side c too you can use law of cosines i guess

Vocaloid:

c^2 = a^2 + b^2 - 2ab * cos(C) you have everything except c, solve for c

Vocaloid:

should be -2ab not -2ac

zarkam21:

c²=a²+b²-2abCos(C) c^2=142.95^2+175^2-2*142.95*175 (Cos(83) c^2=44962.3 c=212.0

Vocaloid:

A+ well done

zarkam21:

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Vocaloid:

well same logic as the previous problem, we are given two angles, how would we find the missing angle A?

zarkam21:

part I -- 180-35-45=20

zarkam21:

for part 2 are we solving for angle B?

zarkam21:

I mean b

Vocaloid:

check your math again 180 - 45 - 35 = 100 not 20 for part II) yes, use law of sines to find side b

zarkam21:

17/sin(100) = b/sin(45)

zarkam21:

b=12.21

Vocaloid:

have to be very careful with your a, b, and c labels|dw:1527178374588:dw|

Vocaloid:

a is always across angle A b is always across angle B c is always across angle C

Vocaloid:

so looking at your diagram a/sin(A) = c/sin(C) = ?

zarkam21:

a/sin(A) = c/sin(C) a/sin(100)=17/sin(35) a=29.2

Vocaloid:

good then for part III) use law of cosines to find b

zarkam21:

b²=a²+c²-2acCos(B) b^2=29.2^2+17^2-2*29.2*17 (cos35) b^2-328.39 b=18.12

Vocaloid:

A+ well done

zarkam21:

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zarkam21:

part I 180-130-30=20

Vocaloid:

good, then use law of sines for part II to find d

zarkam21:

d/sin130=35/sin30

zarkam21:

ugh this :/

Vocaloid:

almost d/sin(130) = 35/sin(20) not 30degrees

zarkam21:

d=78.39

Vocaloid:

good then for part III you can find the missing side (from suzie to the boat) using law of cosines

zarkam21:

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zarkam21:

there is only two parts to this question :/

Vocaloid:

oh ok cool

Vocaloid:

don't forget your units (Feet)

zarkam21:

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zarkam21:

b²=a²+c²-2acCos(B) 21^2=22^2+16^2-2*22*16 (cos B)

zarkam21:

The calc for some reason is not giving me an answer is 299 roght?

Vocaloid:

21^2=22^2+16^2-2*22*16*x try solving for x, then take the arccos of the result

zarkam21:

64.87

Vocaloid:

good then for part II, law of sines to find C

zarkam21:

b/sin(B)=c/sin(C) 21/sin(64.87)=16/Sin(C) C=84.22 degrees

Vocaloid:

hm, try that again 21/sin(64.87)=16/x try solving for x then take the arcsin of the result

zarkam21:

42.84

Vocaloid:

good, then for part III we have angle B and angle C so angle A = 180 - B - C

Vocaloid:

180 - 42.84 - 64.87 = ?

zarkam21:

72.29 sorry I was afk

Vocaloid:

good

zarkam21:

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zarkam21:

b²=a²+c²-2acCos(B) 18^2=

zarkam21:

ugh im confused

Vocaloid:

we want to find side a we have angle A, side b, and side c a^2 = b^2 + c^2 - 2(b)(c)cos(A)

zarkam21:

a^2 = b^2 + c^2 - 2(b)(c)cos(A) a^2=18^2+20^2-2*18*20 (Cos 95)

zarkam21:

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Vocaloid:

check your notation again a^2=18^2+20^2-2*18*20*cos(95)

zarkam21:

1 attachment
Vocaloid:

click the approximate form button

zarkam21:

28.049

Vocaloid:

good so 28.049 feet for part II: plug in d = r*t where d is the distance, r is the speed of car A, t is time, solve for time

zarkam21:

28.049=30*t t=0.93

Vocaloid:

oh whoops that's car B so that would be part III for part II use the distance of car A (18 miles) and the speed from car A (30 mph)

zarkam21:

18=30*t

zarkam21:

like that

Vocaloid:

good

zarkam21:

t=3/5

zarkam21:

for part II

Vocaloid:

good for part III use the distance 28.049 feet and speed 45 mph

zarkam21:

28.049=45*t t=0.62

zarkam21:

would it be seconds?

Vocaloid:

travelling 28 miles in 0.62 would be quite a feat the speed is given in mph so hours not seconds

zarkam21:

so 0.62 hours

Vocaloid:

good so for part IV car B is greater by (0.62-0.60) hours

zarkam21:

0.02

Vocaloid:

good

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