In problems 1 - 15, calculate the derivatives. 1. D( arcsin( 3x ) ) 2. D( arctan( 7x ) ) 3. D( arctan( x + 5 ) ) 4. D( arcsin( x/2 ) ) 5. D( arctan( Vx ) ) 6. D( arcsec( x- ) ) 7. D( In( arctan( x ) ) ) 8. D( Varcsin( x ) ) 9. D( ( arcsec(x) )' ) 20. (a) What is the viewing angle for the tunnel sign in Fig. 24? (b) Use arctangents to 10 ft. sign describe the viewing angle when the observer is x feet from the entrance of the tunnel. 20 ft. tunnel 5 ft. 16 21. (a) What is the viewing angle for the chalk road 40 ft. board in Fig. 25 ? (b) Use arctangents to Fig. 24: On the road describe the viewing angle when the student is x feet from the front wall