# Posts by Evelina

Total # Posts: 17

math
How many solutions equation x^4 + 2x^2 - 15 = 0 has?

math
Helped alot! Thank you!

math

biology
I have codone AUG. Which one of amino acids will be involved in protein making, if nucleotide with adenine (A) will be changed to nucleotide with cytosine (C)?

science
V(CH3OH)= 2 litres ρ(CH3OH) = 0,80 g/ml v(O2) - ? (How much O2 is it needed to burn with 2 litres of CH3OH?)

chemistry
V(CH3OH)= 2 litres ρ(CH3OH) = 0,80 g/ml v(O2) - ? (How much O2 is it needed to burn with 2 litres of CH3OH?)

trig
If (cosa-sina)/sina = 2 , then what is tga = ?

trig
ehh, still don't get it.

trig
I need to prove parallelogram law using the law of cosines. 2AB^2 + 2BC^2 = AC^2 + BD^2 Please, help me to do this.

trig
How to prove the theorem of sines, using S=(a*b/2) * sin γ ?

trig
I need to count this: a) 1-tg^2a/1+ctg^2a, when sina =2/3 b) 1-tg^2a/1-ctg^2a, when cosa= -1/3 c) tga * cos^2a, when sina + cosa=5/7 d) tg^2a + 1/sina * 1/cosa + ctg^2a, when tga + ctga =5

trig
Well, that‘s what the question says. I can send a picture of it, if you don‘t believe. Show me how you do it with brackets, maybe I‘ll know what to do with that one.

trig
The b) actually was like this in my book: sin^2x/sinx-cosx - sinx+cosx/tg^2x+1 = sinx + cosx

trig
I need to prove equality. a) (sina + cosa)^2 -1 / ctga - sinacosa = 2tg^2a b) (sin^2x/sinx-cosx) - (sinx+cosx/tg^2x+1) = sinx + cosx c) sin^4a - sin^2a - cos^4a + cos^2a = cosπ/2 How to do these?

trig
How to do this one? (sina/1-cosa) + (1-cosa/sina) = Also, wanted to ask if I did another one right: 1 - sin^2a + tg^2a * cos^2a = 1 - sin^2a + (sina/cosa)^2 * cos^2a = 1 - sin^2a + sin^2a = 1 ???

trig
oh yes, I wrote the first one wrong. THANK YOU

trig
Please help me how to do this: 1) 1 + sina*cosa / (cosa + sina)^2 = 2) sina + cosa / 1- 2sin^2a =