X= -b⁺₋ √b²-4ac/2a
x= (-(-2)⁺₋√(-2)²- 4(4)(-5))/2(4)
x= 4 ⁺₋√4+80/8
x= (4⁺₋ 9.165)/8
x= 4+9.165)/8 or x= 4-9.165)/8
x= 1.40 or x= -0.896
A=1/(2s) * (v²-u²)
.......,.........
..
Answer:
case A. 
case B. 
case E. 
Step-by-step explanation:
we have
we know that
<u>Verify each case</u>
case A)
therefore
is equivalent to
case B)
so
is equivalent to
case C) 
therefore
is not equivalent to
case D) 
so
is not equivalent to
case E)
therefore
is equivalent to
case F) 
so
is not equivalent to
Answer:
A)
Step-by-step explanation:
1. Given any triangle ABC with sides BC=a, AC=b and AB=c, the following are true :
i) the larger the angle, the larger the side in front of it, and the other way around as well. (Sine Law) Let a=20 in, then the largest angle is angle A.
ii) Given the measures of the sides of a triangle. Then the cosines of any of the angles can be found by the following formula:
a^{2}=b ^{2}+c ^{2}-2bc(cosA)
2.
20^{2}=9 ^{2}+13 ^{2}-2*9*13(cosA) 400=81+169-234(cosA) 150=-234(cosA) cosA=150/-234= -0.641
3. m(A) = Arccos(-0.641)≈130°,
4. Remark: We calculate Arccos with a scientific calculator or computer software unless it is one of the well known values, ex Arccos(0.5)=60°, Arccos(-0.5)=120° etc
