<span>As the age of the U-235 sample is 2.631 billion years, and the half-life of U-235 is 713 million years, the sample has undergone 2.361 X 1,000,000,000 / 713 X 1,000,000 = 3.69 half lives. In each half-life the sample reduces to half its original weight according to the radioactive Half-Life Formula:
ln (Nt /N0) = -kt, where N0 = mass of the original weight of radioactive material, Nt = mass of radioactive material at time t, k = decay constant and t = time interval . We have to put Nt/N0 = 1/2 for time interval = half-life.</span>
Angles are always congruent
SinØ(TanØ+2)=3cosØ -----[pulling like terms out]
for the following steps The easiest 4 me is that I just plug in values between 0° and 180° for Ø and see which will help me to get equal numbers on both sides.
So, for instance if you use Ø=90°, you'll get the following, Sin90(Tan90+2)=3cos90
========> 1(1+2)=3(1) ==> 3=3
so 90° is one of the solutions ur looking for.
hope this was helpful
