Answer:
BC = 19.78
Step-by-step explanation:
using sin(x) rule
sin(54)= 16/BC
sin(54)=0.80
∴0.80=16/BC (divied both side by 0.80)
BC=16/0.80 =19.78
Because this is a triangle and we know that we can use the Pythagorean Theorem to find the hypotenuse we just plug in the numbers. But because you have the hypotenuse already you will subtract the leg from the hypotenuse.
A^2+B^2=C^
16^2+B^2=20^2
256+B^2=400 subtract 256 from both sides
B^2=144 now take the square root of both sides
B=12
The second leg is 12 cm long. Your answer is B, the second answer.
X+5=18
first get rid of the 5
so X+5-5=18-5
which makes X=13
if any questions please ask
Answer: 
Step-by-step explanation:
All that is required here is to substitute x = 2x into the right side in the same way that is done for a numeric value.

Answer: The product of (3x+7) and (x-7) equals 3x^2 + 28x + 49
Step-by-step explanation:
To find the product of (3x+7) and (x-7) means to multiply both variables: To multiply both variables, we first multiply 3x by the expression, x - 7, then multiply 7 by the expression, x - 7.
(3x × x) +( 3x × 7) + (7 × x) + ( 7 × 7)
= 3x^2 + 21x + 7x + 49
= 3x^2 + 28x + 49