We must find UNIQUE combinations because choosing a,b,c,d... is the same as d,c,b,a...etc. For this type of problem you use the "n choose k" formula...
n!/(k!(n-k)!), n=total number of choices available, k=number of choices made..
In this case:
20!/(10!(20-10)!)
20!/(10!*10!)
184756
Step-by-step explanation:
Consider LHS

Apply quotient identies

Multiply the fraction and sine.

Make cos x a fraction with cos x as it denominator.

so

Pythagorean Identity tells us sin squared and cos squared equals 1 so

Apply reciprocal identity.

I only know how to do # 7.
7. 4.5^2 + 6^2 = 7.5^2
20.25 + 36 = 56.25
56.25 = 56.25
yes, the card is a right triangle because A and B added together equals the same as C
Ok this is a pretty easy one.
2=22
3=20
4=18
Step-by-step explanation:
Trigonometry, the branch of mathematics concerned with specific functions of angles and their application to calculations. There are six functions of an angle commonly used in trigonometry. Their names and abbreviations are sine (sin), cosine (cos), tangent (tan), cotangent (cot), secant (sec), and cosecant (csc).