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9² = 12² + 15² - 2 (12) (15) cos (B)
81 = 144 + 225 - 360 cos(B)
81 = 369 - 360 cos (B)
360 cos (B) = 369 - 81
360 cos (B) = 288
cos (B) = 0.8
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Answer: Cosine B = 0.8
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-
12² = 15² + 9² - 2 (15)(9) cos (A)
144 = 225 + 81 - 270 Cos A
144 = 306 - 270 Cos A
270 Cos A = 162
Cos A = 3/5 or 0.6
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Answer: Cosine Angle A = 3/5
Answer:
#5: 180 paperclips in total.
#6: 126 stamps in total.
#7: Elena should give Lucy 15 colored pencils.
Step-by-step explanation:
This explanation solves each question by setting a single unknown, .
Let the initial number of paperclips of Antonio. That should also be the number of Abby's paperclips.
Initially:
Antonio gives paperclips to Abby. After that,
Abby now possess twice as many paperclips as Antonio does. In other words,
.
By the distributive property:
.
Substract from both sides
.
Both Antonio and Abby initially possess 90 paperclips. That's 180 in total.
<h3>#6</h3>Similarly, let be the number of Emily's stamps. That should be the same as the number of Jasmine's stamps.
Initially:
After Emily gives stamps to Jasmine:
Jasmine now possesses twice as many stamps as Emily does. In other words,
.
.
Jasmine used to possess 126 stamps. Now she possesses stamps after receiving
stamps from Emily.
Let the number of pencils that Elena needs to give to Lucy be .
Initially:
After Elena gives pencils to Lucy:
Elena should now possess four more pencils than Lucy does. In other words,
.
.
.