Find the measure of angle B. Show work please

  c.  54.6°

Step-by-step explanation:

The Law of Cosines can be used to find the first of the unknown angles in a triangle with only three side lengths given.

  b² = a² +c² -2ac·cos(B)

Solving for B, we have ...

  2ac·cos(B) = a² +c² -b²

  B = arccos((a² +c² -b²)/(2ac)) = arccos((10.4² +21.9² -18²)/(2(10.4)(21.9)))

  B = arccos(0.579053) ≈ 54.6° . . . . . matches choice C

C 54.6°

Step-by-step explanation:

Using cosine law:

18² = 10.4² + 21.9² - 2(10.4)(21.9)cosB

cosB = 2029/3504

B =54.6160711

225x²+4=0

225x²=0-4

225x²=-4

x²=-4/225

x=±√-4/225

15% chance.

step-by-step explanation:

3/10 times, the 5 year old will get a tablet. 5/10 times, the 13 yer old will get a tablet. multiply both fractions to get 15/100 times, both would have a tablet.