Giúp mình câu 2 nhé.Mình cần gấp lắm mn.Xin hãy giúp mk .Pls
1 answer:
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Answer:
17
Step-by-step explanation:
Using the law of cosines in ΔABC
b² = a² + c² - (2ac cosB) ← substitute in values
= 25² + 28² - (2 × 25 × 28 × cos36.9°)
= 625 + 784 - 1400 cos36.9°
= 1409 - 1400 cos36.9° ( Take the square root of both sides )
b = ≈ 17 ( nearest whole number )
Hello,
s=48t-16t²
a)
s=0==>16t(3-t)=0==>t=0 or t=3
b)
s>32==>48t-16t²>32===>16(t²-3t+2)<0
Δ=9-8=1
==>16(t-1)(t-2)<0
==>1<t<2 (negative between the roots)
s=48t-16t²
a)
s=0==>16t(3-t)=0==>t=0 or t=3
b)
s>32==>48t-16t²>32===>16(t²-3t+2)<0
Δ=9-8=1
==>16(t-1)(t-2)<0
==>1<t<2 (negative between the roots)