Use Double Angle Formula to Find Exact Value Worksheet

Problem 1 :

Given that sin A = 3/5 and cos A = -4/5, find 

i) sin 2A    ii)  cos 2A

Solution

Problem 2 :

Given that sin A = -5/13 and cos A = 12/13, find tan 2A.

Solution

Problem 3 :

If A is acute angle and cos 2A = 3/4, find the values of 

i) cos A 

ii) sin A

Solution

Problem 4 :

If sin A = 4/5 and cos A = 3/5, find the values of 

i) sin 2A

ii) cos 2A

Solution

Problem 5 :

If sin A = -2/3 where π < A < 3π/2, find the value of cos A and hence the value of sin 2A.

Solution

Problem 6 :

If cos A = 2/5, where 3π/2 < A < 2π, find the value of sin A hence find the value of sin 2A.

Solution

Problem 7 :

If A is acute cos 2A = -7/9, find without calculator 

i) cos A

ii) sin A

Solution

Problem 8 :

Find the value of 

Solution

Problem 9 :

Show that

(sin A + cos A)² = 1 + sin 2A

Solution

Problem 10 :

Show that

cos⁴A - sin⁴A = cos 2A

Solution

Solution