In the triangle ABC, a, B and C are the opposite sides of three internal angles a, B and C respectively, and a, B and C are not equal to each other. Let a = 4, C = 3 and a = 2C. (1) find the value of COSC. (2) find the value of B I can do the first question (COSC = 2 / 3), but I can't do the second one

cosC=(a²+b²-c²)/2ac
2/3=(16+b²-9)/24
b²+7=16
b=3

Exponential formula is written as logarithmic formula: 4 ^ x = 1 / 6; 4 ^ x = 2. Please write the process. I just learned logarithm,

The first is x = - in2
Second: x = 1 / 2
If you don't know, you can ask me in detail

We know that the spatial quadrilateral oabc, e Ab.bc If the vector Oh = x vector OA + y vector ob + Z vector OC, then x.y.z. is many

Vector Oh = OE + eh = OE + 1 / 3ef
= OE+1/3(OF-OE)
=1/3OF+2/3OE
=1/3•1/2(OB+OC)+2/3•1/2(OA+OB)
=1/6(OB+OC)+1/3(OA+OB)
=1/3OA+1/2OB+1/6OC.
X=1/3,y=1/2,z=1/6.

1.3 1:2 1 2.7 5 3.1:8 1 4.6 7:3 simplification

1 / 3: 1 / 2
=1\3*6：1\2*6
=2：3
2 out of 5: 5 out of 7
=2\5*35：5\7*35
=14:25
1: One in eight
=1*8：1\8*8
=8：1
7 / 6: 3
=7\6*6：3*6
=7:18

4 / 3 to 1.6

4/3*5/8=5/6
The final answer is five sixths

5 / 6 to 2 / 3
100 / 4 reduction ratio

Five sixths to two thirds
=5/6：2/3
=5：4

√ 162 simplification

√162=√[2x81]=9√2

126:84 simplification

3:2

How to calculate 16.78-2.54 + 3.22-1.46

16.78+3.22-（2.54+1.46）

16.78-2.54+3.22-1.