In the triangle ABC, a, B and C are the opposite sides of the inner angles a, B and C respectively, and satisfy (2b-c) cosa = acosc. 1. Find the size of a: 2. Give three bars

In the triangle ABC, a, B and C are the opposite sides of the inner angles a, B and C respectively, and satisfy (2b-c) cosa = acosc. 1. Find the size of a: 2. Give three bars

(2b-c) Cosa acosc = 0 by the sine theorem B / SINB = A / Sina = C / sinc = 2rb = 2rsinba = 2rsinac = 2rsinc (2b-c) Cosa acosc = 02R (2sinb sinc) cosa-2rsinacosc = 0 (2sinb sinc) Cosa sinacosc = 02sinbcosa sinccosc = 02sinbcosa -

In triangle ABC, cosa = 1 / 3. Calculate Tan (a + 45 degrees)

This should be the trigonometric function problem in the second volume of high school mathematics
First of all, this is the angle in the triangle,
So the angle a is between 0 and 180,
That is to say, the sine of angle a is positive
From the sum of squares of sine and cosine of the same angle = 1, we can calculate the root sign 2 where Sina = 2 / 3
That is, Tana = Sina / cosa = 2, radical 2
Then we can know from the formula of tangent sum angle
Tan (a + 45 ') = (Tana + tan45') / (1-tanatan45 ') (I use' for degree)
Substitute Tana = 2, radical 2 and tan45 '= 1 into the above formula,
You should know the answer