Express tan 1421◦ as a trigonometric function of an angle in Quadrant 1?

subtract multiple of 180 as tan has a period 180 dgrees

1421 mod 180 = 161

this is in qudarnt 2

so tan 161 = - tan 19

so it is - tan 19

the cos(3pi/8 + 3pi) is a sum/distinction of angles if u combine 3pi/8 with 3pi its 27pi/8 pi confuses u, think of of it as time-honored x so 27x/8 first take as plenty x from 27 by dividing 8 so there are 3x and 3 the rest so initiate it with ( ? + 3x) the rest is 3 so positioned it with x/8 so its (3x/8 + 3x) if u examine it , least trouble-free denominator (3x/8 + 24x/8) = 27x/8 substitute x's back to pi won't be defined fairly nicely, i desire it helped you

ans= -tan 19degrees

tan1421*=

-tan19*