The answer is for 1st question is “10.4” and for the second question “non of these choices are correct”.
Explanation:
For the 1st question:
tan = opposite / adjacent
tan 30 = x / 18
18 tan 30 = x
x = 10.4
For the 2nd question,
If a triangle as an angle of 90 degree, it is 100% a right triangle.
Hope it helps :), mark me brainliest please!
It should be B because is a minus is in front of something that is a negative they change to be positive
The amount of substance left of a radioactive element of half life,

after a time, t, is given by:

Given that <span>potassium-40 has a half life of approximately 1.25 billion
years.
The number of years it will take for 0.1% of potassium-40 to remain is obtained as follows:

Therefore, </span><span>the maximum age of a fossil that we could date using 40k is
12.5 billion years.</span>
Answer:
b=5V2
Step-by-step explanation:
Area =31 1/4 = b*12.5 sin45/2=b*12.5*V2/2* 1/2=12.5V2/4 *b
(31*4+1)/4=125/4
so 125/4= 12.5V2*b/4
12.5V2*b=125
b=125/12.5V2=10/V2=10V2/2=5V2