Answer:
Cos 74°= Sin 16°
Sin 20°= Cos 70°
Sin A°=Cos (90°- A°)
Step-by-step explanation:
This is because the three pairs are complementary i.e they add up to 90° and in trigonometric ratios, complementary ratios are equal.
 
        
             
        
        
        
Answer:
Step-by-step explanation:
90.9^2 - 21.2^2 = b^2
8,262.81 - 449.44 = b^2
b = 88.39326897450959189749074160142
 
        
             
        
        
        
The expression for the cost of the ABC Book Club is 2<em>x </em>+ 40.  The expression for the cost of the Easy Book Club is 3<em>x</em> + 35.  To find when the total charge for both book clubs is equal, the two expressions must equal each other. (<em>x </em>= the number of books read)
2<em>x </em>+ 40 = 3<em>x</em> + 35
Subtract 35 from both sides.
2<em>x </em>+ 5 = 3x
Subtract 2<em>x </em>from both sides.
5 = <em>x</em>
So, the total charge for each club is equal when 5 books are read.