Question

please help
no short answer
solve it on paper and send the pic
class 11 maths chapter 3 Trigonometry​

Answer 1

Answer:

6) tan A + tan B = (tanA+tanB) / (1 - tanA*tanB)

⇒(tan69 + tan 66) / (1 - tan69*tan66) = tan(69+66)

= tan(135)

= tan(180-45)

= -(tan45)

= -1 (proved)

5) cos A = -24/25 ,  cosB = 3/5

cos(A+B) = cosAcosB - sinAsinB

A is in 3Rd quadrant

B is in 4th quadrant

sin A = - $\sqrt{1-cos^{2}A }$

= - sqrt (1 -(-24/25)² )

= - ($\sqrt{49/625\\}$)

= -7/25

sin B = - $\sqrt{1-cos^{2}B }$

   = - $\sqrt{1-(3/5)^{2} }$

= -4/5

cos(A+B) = (-24/25 * 3/5) - (-7/25 * -4/5)

= - 100/125

= - 4/5

Hope this helps. Happy learning!!!