In a classic Conan Doyle story, Sherlock Holmes solves a crime mystery by recognizing that a guard dog didn't bark. Therefore, the dog must have known the perpetrator. Holmes' reasoning goes like this: if the guard dog doesn't know a person, then it barks. The dog didn't bark. Therefore, it knew the person. Which rule of inference is being used here?

a. Addition.
b. Simplification.
c. Conjunction.
d. Modus Ponens.
e. Hypothetical Syllogism.
f. Disjunctive Syllogism.
g. Modus Tollens.
h. Resolution.

G. Modus tollens

Step-by-step explanation:

This question used the inference called modus tollens.

Modus tollens is a a valid form of argument that is of this form below:

If S, then T

if not S, then not T.

S = dog doesn't know perpetrator

Not S = dog knows who the perpetrator is

T = the dog barked

Not T = the dog did not bark.

So if we put this into the statement in bold letters, we would have:

The dog doesn't know perpetrator, so it barked.

And,

The dog didn't bark, so it knows the perpetrator.

la parábola es el lugar

geométrico en el cual los puntos tienen una distancia idéntica, equidistantes,

de un punto denominado foco, f, y una recta denominada directriz

el radio vector de una

parábola es el segmento que existe entre un punto cualquiera y el foco.

por la ecuación se observa

que la parábola abre hacia la derecha, por lo cual podemos usar las siguientes fórmulas

la ecuación ordinaria de la

parábola es y^2 = 4px, donde p es la longitud desde el vértice de la parábola al

foco.

la fórmula de la directriz

es x + p = 0

resolviendo:

y^2-9x = 0

y^2 = 9x

4p = 9, entonces p = 9/4

entonces el foco tendrá la

coordenada f(9/4,0)

la directriz vendrá

expresada por

x + p = 0

x = -p

x = -9/4

el problema indica que la

ordenada es igual a 6, entonces

(6)^2=9x

x = 36/9

x = 4

entonces el punto al cual

hay que obtener la distancia será p(4,6)

calculando se tendrá: pf = 

pf = 6,25 u

ver más en -

step-by-step explanation:

11.2

step-by-step explanation:

when doing tangent the tangent of the angle is equal to the opposite side from the angle over the adjacent side to the angle.

tan43 = x / 12

move 12 over by multiplying each side by 12

12tan43 = x

x = about 11.2