If and , how can I prove that ?
Using a calculator to find inverse sine and tangent then subtracting the angles gets 45 degrees, but I do not think that is the correct way to approach the question.
Similar questions are find etc.
I think when I get the method I should be fine in doing these questions. Thanks!
You might try using simple sketches.
Then, draw a simple right angled triangle, with hypotenuse [/tex]\sqrt5[/tex], opposite side 2 and adjacent side 1.
Ah, coincidence, the angle opposite to the angle A is the angle B!
Now that you know all the trigonometric ratios of A and B, you can use any identity you know;
or the tangent ratio given by sa-ri-ga-ma.
For cos and sin, you should get
For tan, you should get tan(A-B) = 1.
For the second question, provided you know A, B, or one trigonometric identity of A and B, you use the identity:
Where, you replace A by (A+B) and B by C.
Then, you can use the identity : to solve for C.