Question

Helppp

Answer 1

Sam used his calculator to find cos 1.75.
Part I: When no unit is given for an angle, what unit must be used? (2 points)


Part II: In what quadrant is an angle of 1.75 found? (2 points)




Part III: In this quadrant, is the value of cosine positive or negative? (2 points)




Part IV: Sam used his calculator to find the answer and wrote down cos 1.75 = 0.999. Does this seem like a reasonable answer to you (2 points)




Part V: What might he have done wrong on his calculator (4 points)

Answer 2

part I) [you kind of just have to memorize this, but in math we default to ~radians~ as the unit if no unit is given]

Answer 3

part II - convert 1.75 radians to degrees, then state what quadrant it's in

Answer 4

okay so part I is radians
part II 1.75 radians is 100.26 degree
quadrant III

Answer 5

check the quadrant again

Answer 6

our angle is between 90 and 180 so which quadrant?

Answer 7

quadrant I

Answer 8

oh shoot i got confused that's the one I meant

Answer 9

yup good

for part IV - any guesses? judging by the quadrant, what sign would cos have to be?

Answer 10

*** part III sorry

Answer 11

positive

Answer 12

if you think about it like a regular x-y coordinate plane

would the x coordinate of this point be positive or negative?

Answer 13

neg

Answer 14

good so part III) cos would be negative

Answer 15

part IV) based on that, do you think cos(1.75) = 0.999 is a reasonable answer?

Answer 16

no

Answer 17

good! since cos must be negative then 0.999 can't be it since it's positive

Answer 18

Part V - calculator error -

any ideas? the error he made is a very common mistake when dealing with angles

Answer 19

um

Answer 20

has something to do with units

Answer 21

is in degree mode

Answer 22

awesome! so part V) "he left his calculator in degree mode so the calculator interpreted it as 1.75 degrees not radians"

and that's it ~