切线问题

Question

Okay, the tangent I'm talking about isn't tangent inverse, but the tangent that is able to solve missing angle lengths in a right triangle. So far, I've been able to divide the opposite leg by a adjacent length.

#this is for a 6,8, 10 triangle!
#y is 8, x is 6
#if you look on the table, 1.3333 is near 53 degrees

if(a==b):
print("This is a right triagle b/c the legs are equal to the hypotnuse!")

tan = input("Would you like to find the tangent of angle A? : ")
if(tan=="Yes"):
    print("Lets do this!")
    #works with 6,8,10 triangle for now!
    print(y,"/",x)
    tan = (str(float(y)/float(x)))
    round(float(tan),3)
    print(round(float(tan),3))
    print("Looking for rounded tan in table!")
    #remember that 1.333 is near 53 degrees (see on trig table)
    if(tan == 1.333):
        print("<A == ", 53)
        print("<B ==  90")
        c = str(int(53)+int(90))
        c2 = str(int(180)-int(c))
        print("<C == ",c2)
    else:
        print("Nope")

elif(tan=="No"):
    print("See you!")
    exit(0);

For some reason, the program will only use the else statement, and say nope. Please help! THANKS so much in advance.

Answer 1

You're not updating tan after rounding . Note that float objects are immutable and round returns a numeric type; there isn't an in-place update of tan after rounding.

You need an assignment to rebind the returned float object to tan :

tan = round(float(tan), 3)

Answer 2

There are multiple problems here:

• tan is a string, so it will never equal a floating point number. Note that you only assign to tan once. The output of your rounding operations is either printed or discarded but not stored in tan . You probably want something like this:

   tan = round(float(y) / float(x), 3) 

• You compare against a floating point number with == . You should never check equality with floating point numbers! (unless you assign them as literals.) You should instead always check how close two numbers are:

   if abs(tan - 1.333) < 1e5: 

• Also: Don't convert anything to strings, unless you need to operate on the string (eg, index it). Why don't you use Python math functions?